Tagged Obesity

Exercise vs. Diet? What Children of the Amazon Can Teach Us About Weight Gain

A young girl carries harvested food, part of the traditional hunting and gathering lifestyle of the Shuar of Amazonian Ecuador.
A young girl carries harvested food, part of the traditional hunting and gathering lifestyle of the Shuar of Amazonian Ecuador.Credit…Samuel S. Urlacher, Ph.D.

Phys Ed

Exercise vs. Diet? What Children of the Amazon Can Teach Us About Weight Gain

What we eat may be more important than how much we move when it comes to fighting obesity.

A young girl carries harvested food, part of the traditional hunting and gathering lifestyle of the Shuar of Amazonian Ecuador.Credit…Samuel S. Urlacher, Ph.D.

Gretchen Reynolds

  • Feb. 24, 2021, 5:00 a.m. ET

When children gain excess weight, the culprit is more likely to be eating too much than moving too little, according to a fascinating new study of children in Ecuador. The study compared the lifestyles, diets and body compositions of Amazonian children who live in rural, foraging communities with those of other Indigenous children living in nearby towns, and the results have implications for the rising rates of obesity in both children and adults worldwide.

The in-depth study found that the rural children, who run, play and forage for hours, are leaner and more active than their urban counterparts. But they do not burn more calories day-to-day, a surprising finding that implicates the urban children’s modernized diets in their weight gain. The findings also raise provocative questions about the interplay of physical activity and metabolism and why exercise helps so little with weight loss, not only in children but the rest of us, too.

The issue of childhood obesity is of pressing global interest, since the incidence keeps rising, including in communities where it once was uncommon. Researchers variously point to increasing childhood inactivity and junk food diets as drivers of youthful weight gain. But which of those concerns might be more important — inactivity or overeating — remains murky and matters, as obesity researchers point out, because we cannot effectively respond to a health crisis unless we know its causes.

That question drew the interest of Sam Urlacher, an assistant professor of anthropology at Baylor University in Waco, Texas, who for some time has been working among and studying the Shuar people. An Indigenous population in Amazonian Ecuador, the traditional Shuar live primarily by foraging, hunting, fishing and subsistence farming. Their days are hardscrabble and physically demanding, their diets heavy on bananas, plantains and similar starches, and their bodies slight. The Shuar, especially the children, are rarely overweight. They also are not often malnourished.

But were their wiry frames a result mostly of their active lives, Dr. Urlacher wondered? As a postgraduate student, he had worked with Herman Pontzer, an associate professor of evolutionary anthropology at Duke University, whose research focuses on how evolution may have shaped our metabolisms and vice versa.

In Dr. Pontzer’s pioneering research with the Hadza, a tribe of hunter-gatherers in Tanzania, he found that, although the tribespeople moved frequently during the day, hunting, digging, dragging, carrying and cooking, they burned about the same number of total calories daily as much-more-sedentary Westerners.

Dr. Pontzer concluded that, during evolution, we humans must have developed an innate, unconscious ability to reallocate our body’s energy usage. If we burn lots of calories with, for instance, physical activity, we burn fewer with some other biological system, such as reproduction or immune responses. The result is that our average, daily energy expenditure remains within a narrow band of total calories, helpful for avoiding starvation among active hunter-gatherers, but disheartening for those of us in the modern world who find that more exercise does not equate to much, if any, weight loss. (Dr. Pontzer’s highly readable new book on this topic, “Burn,” will be published on March 2. )

A young Shuar boy fills a water gourd in the river.
A young Shuar boy fills a water gourd in the river.Credit…Samuel S. Urlacher, Ph.D.

Dr. Pontzer’s work focuses primarily on Hadza adults, but Dr. Urlacher wondered if similar metabolic trade-offs might also exist in children, including among the traditional Shuar. So, for a 2019 study, he precisely measured energy expenditure in some of the young Shuar and compared the total number of calories they incinerated with existing data about the daily calories burned by relatively sedentary (and much heavier) children in the United States and Britain. And the totals matched. Although the young Shuar were far more active, they did not burn more calories, over all.

Young Shuar differ from most Western children in so many ways, though, including their genetics, that interpreting that study’s findings was challenging, Dr. Urlacher knew. But he also was aware of a more-comparable group of children only a longish canoe ride away, among Shuar families that had moved to a nearby market town. Their children regularly attended school and ate purchased foods but remained Shuar.

So, for the newest study, which was published in January in The Journal of Nutrition, he and his colleagues gained permission from Shuar families, both rural and relatively urban, to precisely measure the body compositions and energy expenditure of 77 of their children between the ages of 4 and 12, while also tracking their activities with accelerometers and gathering data about what they ate.

The urban Shuar children proved to be considerably heavier than their rural counterparts. About a third were overweight by World Health Organization criteria. None of the rural children were. The urban kids also generally were more sedentary. But all of the children, rural or urban, active or not, burned about the same number of calories every day.

What differed most were their diets. The children in the market town ate far more meat and dairy products than the rural children, along with new starches, like white rice, and highly processed foods, like candy. In general, they ate more and in a more-modern way than the rural children, and it was this diet, Dr. Urlacher and his colleagues conclude, that contributed most to their higher weight.

These findings should not romanticize the forager or hunter-gatherer lifestyle, Dr. Urlacher cautions. Rural, traditional Shuar children face frequent parasitic and other infections, as well as stunted growth, in large part because their bodies seem to shunt available calories to other vital functions and away from growing, Dr. Urlacher believes.

But the results do indicate that how much children eat influences their body weight more than how much they move, he says, an insight that should start to guide any efforts to confront childhood obesity.

“Exercise is still very important for children, for all sorts of reasons,” Dr. Urlacher says. “But keeping physical activity up may not be enough to deal with childhood obesity.”

How Meaningful Is Prediabetes for Older Adults?

the new old age

How Meaningful Is Prediabetes for Older Adults?

A new study indicates that the condition might be less of a worry than once believed.

Susan Glickman Weinberg, of Encino, Calif., was told a few years ago during routine tests that she was prediabetic, a diagnosis that puzzled her. “I felt like Patient Zero,” she said. “There were a lot of unknowns.”
Susan Glickman Weinberg, of Encino, Calif., was told a few years ago during routine tests that she was prediabetic, a diagnosis that puzzled her. “I felt like Patient Zero,” she said. “There were a lot of unknowns.”Credit…Jenna Schoenefeld for The New York Times

  • Feb. 23, 2021, 2:30 a.m. ET

A few years ago, routine lab tests showed that Susan Glickman Weinberg, then a 65-year-old clinical social worker in Los Angeles, had a hemoglobin A1C reading of 5.8 percent, barely above normal.

“This is considered prediabetes,” her internist told her. A1C measures how much sugar has been circulating in the bloodstream over time. If her results reached 6 percent — still below the number that defines diabetes, which is 6.5 — her doctor said he would recommend the widely prescribed drug metformin.

“The thought that maybe I’d get diabetes was very upsetting,” recalled Ms. Weinberg, who as a child had heard relatives talking about it as “this mysterious terrible thing.”

She was already taking two blood pressure medications, a statin for cholesterol and an osteoporosis drug. Did she really need another prescription? She worried, too, about reports at the time of tainted imported drugs. She wasn’t even sure what prediabetes meant, or how quickly it might become diabetes.

“I felt like Patient Zero,” she said. “There were a lot of unknowns.”

Now, there are fewer unknowns. A longitudinal study of older adults, published online this month in the journal JAMA Internal Medicine, provides some answers about the very common in-between condition known as prediabetes.

The researchers found that over several years, older people who were supposedly prediabetic were far more likely to have their blood sugar levels return to normal than to progress to diabetes. And they were no more likely to die during the follow-up period than their peers with normal blood sugar.

“In most older adults, prediabetes probably shouldn’t be a priority,” said Elizabeth Selvin, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health in Baltimore and the senior author on the study.

Prediabetes, a condition rarely discussed as recently as 15 years ago, refers to a blood sugar level that is higher than normal but that has not crossed the threshold into diabetes. It is commonly defined by a hemoglobin A1C reading of 5.7 to 6.4 percent or a fasting glucose level of 100 to 125 mg/dL; in midlife, it can portend serious health problems.

A diagnosis of prediabetes means that you are more likely to develop diabetes, and “that leads to downstream illness,” said Dr. Kenneth Lam, a geriatrician at the University of California, San Francisco, and an author of an editorial accompanying the study. “It damages your kidneys, your eyes and your nerves. It causes heart attack and stroke,” he said.

But for an older adult just edging into higher blood sugar levels, it’s a different story. Those fearful consequences take years to develop, and many people in their 70s and 80s will not live long enough to encounter them.

That fact has generated years of debate. Should older people with slightly above-normal blood sugar readings — a frequent occurrence since the pancreas produces less insulin in later life — be taking action, as the American Diabetes Association has urged?

Or does labeling people prediabetic merely “medicalize” a normal part of aging, creating needless anxiety for those already coping with multiple health problems?

Dr. Selvin and her colleagues analyzed the findings of an ongoing national study of cardiovascular risk that began in the 1980s. When 3,412 of the participants showed up for their physicals and lab tests between 2011 and 2013, they had reached ages 71 to 90 and did not have diabetes.

Prediabetes, however, was rampant. Almost three-quarters qualified as prediabetic, based on either their A1C or fasting blood glucose levels.

These findings mirrored a 2016 study pointing out that a popular online risk test created by the Centers for Disease Control and Prevention and the American Diabetes Association, called doihaveprediabetes.org, would deem nearly everyone over 60 as prediabetic.

In 2010, a C.D.C. review reported that 9 to 25 percent of those with an A1C of 5.5 to 6 percent will develop diabetes over five years; so will 25 to 50 percent of those with A1C readings of 6 to 6.5. But those estimates were based on a middle-aged population.

When Dr. Selvin and her team looked at what had actually happened to their older prediabetic cohort five to six years later, only 8 or 9 percent had developed diabetes, depending on the definition used.

A much larger group — 13 percent of those whose A1C level was elevated and 44 percent of those with prediabetic fasting blood glucose — actually saw their readings revert to normal blood sugar levels. (A Swedish study found similar results.)

Sixteen to 19 percent had died, about the same proportion as those without prediabetes.

“We’re not seeing much risk in these individuals,” Dr. Selvin said. “Older adults can have complex health issues. Those that impair quality of life should be the focus, not mildly elevated blood glucose.”

Carol Jacobi, a friend of Ms. Weinberg’s, received a similar diagnosis at around the same time, but did nothing much to reduce her blood sugar.
Carol Jacobi, a friend of Ms. Weinberg’s, received a similar diagnosis at around the same time, but did nothing much to reduce her blood sugar.Credit…Jenna Schoenefeld for The New York Times

Dr. Saeid Shahraz, a health researcher at Tufts Medical Center in Boston and lead author of the 2016 study, praised the new research. “The data is really strong,” he said. “The American Diabetes Association should do something about this.”

It may, said Dr. Robert Gabbay, the A.D.A.’s chief scientific and medical officer. The organization currently recommends “at least annual monitoring” for people with prediabetes, a referral to the lifestyle modification programs shown to decrease health risks and perhaps metformin for those who are obese and under 60.

Now the association’s Professional Practice Committee will review the study, and “it could lead to some adjustments in the way we think about things,” Dr. Gabbay said. Among older people considered prediabetic, “their risk may be smaller than we thought,” he added.

Defenders of the emphasis on treating prediabetes, which is said to afflict one-third of the United States population, point out that first-line treatment involves learning healthy behaviors that more Americans should adopt anyway: weight loss, smoking cessation, exercise and healthy eating.

“I’ve had a number of patients diagnosed with prediabetes, and it’s what motivates them to change,” Dr. Gabbay said. “They know what they should be doing, but they need something to kick them into gear.”

Geriatricians tend to disagree. “It’s unprofessional to mislead people, to motivate them by fear of something that’s not actually true,” Dr. Lam said. “We’re all tired of having things to be afraid of.”

He and Dr. Sei Lee, a coauthor of the editorial accompanying the new study and a fellow geriatrician at the University of California, San Francisco, argue for a case-by-case approach in older adults — especially if a diagnosis of prediabetes will cause their children to berate them over every cookie.

For a patient who is frail and vulnerable, “you’re likely dealing with a host of other problems,” Dr. Lam said. “Don’t worry about this number.”

A very healthy 75-year-old who could live 20 more years faces a more nuanced decision. She may never progress to diabetes; she may also already follow the recommended lifestyle modifications.

Ms. Weinberg, now 69, sought help from a nutritionist, changed her diet to emphasize complex carbohydrates and protein, and began walking more and climbing stairs instead of taking elevators. She shed 10 pounds she didn’t need to lose. Over 18 months, her barely elevated A1C reading fell to 5.6.

Her friend Carol Jacobi, 71, who also lives in Los Angeles, got a similar warning at about the same time. Her A1C was 5.7, the lowest number defined as prediabetic, but her internist immediately prescribed metformin.

Ms. Jacobi, a retired fund-raiser with no family history of diabetes, felt unconcerned. She figured she could lose a little weight, but she had normal blood pressure and an active life that included lots of walking and yoga. After trying the drug for a few months, she stopped.

Now, neither woman has prediabetes. Although Ms. Jacobi did nothing much to reduce her blood sugar, and has gained a few pounds during the pandemic, her A1C has fallen to normal levels, too.

Are Some Foods Addictive

Are Addictive Foods Making Us Fat?

Food researchers debate whether highly processed foods like potato chips and ice cream are addictive, triggering our brains to overeat.

Credit…Richard A. Chance
Anahad O’Connor

  • Feb. 18, 2021, 5:00 a.m. ET

Five years ago, a group of nutrition scientists studied what Americans eat and reached a striking conclusion: More than half of all the calories that the average American consumes comes from ultra-processed foods, which they defined as “industrial formulations” that combine large amounts of sugar, salt, oils, fats and other additives.

Highly processed foods continue to dominate the American diet, despite being linked to obesity, heart disease, Type 2 diabetes and other health problems. They are cheap and convenient, and engineered to taste good. They are aggressively marketed by the food industry. But a growing number of scientists say another reason these foods are so heavily consumed is that for many people they are not just tempting but addictive, a notion that has sparked controversy among researchers.

Recently, the American Journal of Clinical Nutrition explored the science behind food addiction and whether ultra-processed foods might be contributing to overeating and obesity. It featured a debate between two of the leading experts on the subject, Ashley Gearhardt, associate professor in the psychology department at the University of Michigan, and Dr. Johannes Hebebrand, head of the department of child and adolescent psychiatry, psychosomatics and psychotherapy at the University of Duisburg-Essen in Germany.

Dr. Gearhardt, a clinical psychologist, helped develop the Yale Food Addiction Scale, a survey that is used to determine whether a person shows signs of addictive behavior toward food. In one study involving more than 500 people, she and her colleagues found that certain foods were especially likely to elicit “addictive-like” eating behaviors, such as intense cravings, a loss of control, and an inability to cut back despite experiencing harmful consequences and a strong desire to stop eating them.

At the top of the list were pizza, chocolate, potato chips, cookies, ice cream, French fries and cheeseburgers. Dr. Gearhardt has found in her research that these highly processed foods share much in common with addictive substances. Like cigarettes and cocaine, their ingredients are derived from naturally occurring plants and foods that are stripped of components that slow their absorption, such as fiber, water and protein. Then their most pleasurable ingredients are refined and processed into products that are rapidly absorbed into the bloodstream, enhancing their ability to light up regions of the brain that regulate reward, emotion and motivation.

Salt, thickeners, artificial flavors and other additives in highly processed foods strengthen their pull by enhancing properties like texture and mouth-feel, similar to the way that cigarettes contain an array of additives designed to increase their addictive potential, said Dr. Gearhardt. Menthol helps to mask the bitter flavor of nicotine, for example, while another ingredient used in some cigarettes, cocoa, dilates the airways and increases nicotine’s absorption.

A common denominator among the most irresistible ultra-processed foods is that they contain large amounts of fat and refined carbohydrates, a potent combination that is rarely seen in naturally occurring foods that humans evolved to eat, such as fruits, vegetables, meat, nuts, honey, beans and seeds, said Dr. Gearhardt. Many foods found in nature are rich in either fat or carbs, but typically they are not high in both.

“People don’t experience an addictive behavioral response to naturally occurring foods that are good for our health, like strawberries,” said Dr. Gearhardt, director of the Food and Addiction Science and Treatment lab at the University of Michigan. “It’s this subset of highly processed foods that are engineered in a way that’s so similar to how we create other addictive substances. These are the foods that can trigger a loss of control and compulsive, problematic behaviors that parallel what we see with alcohol and cigarettes.”

In one study, Dr. Gearhardt found that when people cut back on highly processed foods, they experienced symptoms that were comparable to the withdrawal seen in drug abusers, such as irritability, fatigue, feelings of sadness and cravings. Other researchers have found in brain imaging studies that people who frequently consume junk foods can develop a tolerance to them over time, leading them to require larger and larger amounts to get the same enjoyment.

In her clinical practice, Dr. Gearhardt has encountered patients — some obese and some not — who struggle in vain to control their intake of highly processed foods. Some attempt to eat them in moderation, only to find that they lose control and eat to the point of feeling ill and distraught. Many of her patients find that they cannot quit these foods despite struggling with uncontrolled diabetes, excessive weight gain and other health problems.

“The striking thing is that my clients are almost always acutely aware of the negative consequences of their highly processed food consumption, and they have typically tried dozens of strategies like crash diets and cleanses to try and get their relationship with these foods under control,” she said. “While these attempts might work for a short time, they almost always end up relapsing.”

But Dr. Hebebrand disputes the notion that any food is addictive. While potato chips and pizza can seem irresistible to some, he argues that they do not cause an altered state of mind, a hallmark of addictive substances. Smoking a cigarette, drinking a glass of wine or taking a hit of heroin, for instance, causes an immediate sensation in the brain that foods do not, he says.

“You can take any addictive drug, and it’s always the same story that almost everyone will have an altered state of mind after ingesting it,” said Dr. Hebebrand. “That indicates that the substance is having an effect on your central nervous system. But we are all ingesting highly processed foods, and none of us is experiencing this altered state of mind because there’s no direct hit of a substance in the brain.”

In substance use disorders, people become dependent on a specific chemical that acts on the brain, like the nicotine in cigarettes or the ethanol in wine and liquor. They initially seek out this chemical to get a high, and then become dependent on it to alleviate depressed and negative emotions. But in highly processed foods, there is no one compound that can be singled out as addictive, Dr. Hebebrand said. In fact, evidence suggests that obese people who overeat tend to consume a wide range of foods with different textures, flavors and compositions. Dr. Hebebrand argued that overeating is driven in part by the food industry marketing more than 20,000 new products every year, giving people access to a seemingly endless variety of foods and beverages.

“It’s the diversity of foods that is so appealing and causing the problem, not a single substance in these foods,” he added.

Those who argue against food addiction also point out that most people consume highly processed foods on a daily basis without showing any signs of addiction. But Dr. Gearhardt notes that addictive substances do not hook everyone who consumes them. According to research, about two-thirds of people who smoke cigarettes go on to become addicted, while a third do not. Only about 21 percent of people who use cocaine in their lifetimes become addicted, while just 23 percent of people who drink alcohol develop a dependence on it. Studies suggests that a wide range of factors determine whether people become addicted, including their genetics, family histories, exposure to trauma, and environmental and socioeconomic backgrounds.

“Most people try addictive substances and they don’t become addicted,” Dr. Gearhardt said. “So if these foods are addictive, we wouldn’t expect that 100 percent of society is going to be addicted to them.”

For people who struggle with limiting their intake of highly processed foods, Dr. Gearhardt recommends keeping a journal of what you eat so you can identify the foods that have the most pull — the ones that cause intense cravings and that you can’t stop eating once you start. Keep those foods out of your home, while stocking your fridge and pantry with healthier alternatives that you enjoy, she said.

Keep track of the triggers that lead to cravings and binges. They could be emotions like stress, boredom and loneliness. Or it could be the Dunkin’ Donuts that you drive by three times a week. Make a plan to manage those triggers by a taking a different route home, for example, or by using nonfood activities to alleviate stress and boredom. And avoid skipping meals, because hunger can set off cravings that lead to regrettable decisions, she said.

“Making sure you are regularly fueling your body with nutritious, minimally processed foods that you enjoy can be important for helping you navigate a very challenging food environment,” said Dr. Gearhardt.

Weekly Health Quiz: Weight Loss, Masks and Covid Vaccines

1 of 7

For the first time, a clinical trial suggested that a drug may be highly effective in promoting weight loss, with obese participants losing, on average, 15 percent of their body weight. The drug tested is called:

Orlistat

Semaglutide

Lorcaserin

Phentermine-topiramate

2 of 7

The percentage of Americans who have received at least one Covid vaccine shot is now around:

5 percent

10 percent

20 percent

30 percent

3 of 7

Dr. Anthony Fauci predicted that most Americans would be eligible to get a Covid vaccine as early as:

March

April

May

June

4 of 7

This state surpassed New York with the highest number of Covid deaths since the start of the pandemic:

Florida

New Jersey

California

Texas

5 of 7

This state has had the lowest total number of Covid deaths overall:

Alaska

Hawaii

Maine

Vermont

6 of 7

The Centers for Disease Control and Prevention urged Americans to wear this type of mask to protect against the spread of coronavirus:

A well fitting surgical mask, or a cloth mask over a surgical mask

An N95 mask

A KN94 mask

The C.D.C. does not endorse the use of masks

7 of 7

A large study found that people with this condition were twice as likely to get Covid:

Asthma

Autoimmune conditions

Hypertension

Dementia

The Best Time of Day to Exercise

Phys Ed

The Best Time of Day to Exercise

Men at risk for diabetes had greater blood sugar control and lost more belly fat when they exercised in the afternoon than in the morning.

Credit…Getty Images
Gretchen Reynolds

  • Jan. 27, 2021, 5:00 a.m. ET

Is it better for our bodies to work out at certain times of day?

A useful new study of exercise timing and metabolic health suggests that, at least for some people, the answer is a qualified yes. The study, which looked at men at high risk for Type 2 diabetes, found that those who completed afternoon workouts upped their metabolic health far more than those who performed the same exercise earlier in the day. The results add to growing evidence that when we exercise may alter how we benefit from that exercise.

Scientists have known for some time that the chronology of our days influences the quality of our health. Studies in both animals and people indicate that every tissue in our bodies contains a kind of molecular clock that chimes, in part, in response to biological messages related to our daily exposure to light, food and sleep.

These cellular clocks then help to calibrate when our cells divide, fuel up, express genes and otherwise go about their normal biological work. Tuned by our lifestyles, these clocks create multiple circadian rhythms inside of us that prompt our bodies’ temperatures, hormone levels, blood sugar, blood pressure, muscular strength and other biological systems to dip and crest throughout the day.

Circadian science also shows that disrupting normal, 24-hour circadian patterns can impair our health. People working overnight shifts, for instance, whose sleep habits are upended, tend to be at high risk for metabolic problems such as obesity and Type 2 diabetes. The same is true for people who eat late at night, outside usual dinner hours. More encouraging research suggests, though, that manipulating the timing of sleep and meals can improve metabolic health.

But much of this research focused on when we eat or go to bed. Whether, and how, exercise timing might influence metabolic health has been less clear, and the results of past experiments have not always agreed. Some suggest that morning workouts, for instance, amplify fat burning and weight loss.

But those experiments often manipulated the timing of breakfast and other meals, as well as exercise, making it difficult to tease out the particular, circadian effects of workouts. They also typically involved healthy volunteers, without metabolic problems.

A much-discussed 2019 study, on the other hand, found that men with Type 2 diabetes who completed a few minutes of high-intensity interval sessions in the afternoon substantially improved their blood-sugar control after two weeks. If they did the same, intense workouts in the morning, however, their blood-sugar levels actually spiked in an unhealthy fashion.

Patrick Schrauwen, a professor of nutrition and movement sciences at Maastricht University Medical Center in the Netherlands, read that 2019 study with interest. He and his colleagues had been studying moderate exercise in people with Type 2 diabetes, but in their research, they had not considered the possible role of timing. Now, seeing the varying impacts of the intense workouts, he wondered if the timing of moderate workouts might likewise affect how the workouts changed people’s metabolisms.

Fortuitously, he and his colleagues had a ready-made source of data, in their own prior experiment. Several years earlier, they had asked adult men at high risk for Type 2 diabetes to ride stationary bicycles at the lab three times a week for 12 weeks, while the researchers tracked their metabolic health. The scientists also, incidentally, had noted when the riders showed up for their workouts.

Now, Dr. Schrauwen and his colleagues pulled data for the 12 men who consistently had worked out between 8 and 10 a.m. and compared them with another 20 who always exercised between 3 and 6 p.m. They found that the benefits of afternoon workouts decisively trumped those of morning exercise.

After 12 weeks, the men who had pedaled in the afternoon displayed significantly better average insulin sensitivity than the morning exercisers, resulting in a greater ability to control blood sugar. They also had dropped somewhat more fat from around their middles than the morning riders, even though everyone’s exercise routines had been identical.

“I believe that doing exercise is better than not doing exercise, irrespective of timing,” Dr. Schrauwen says. “However, this study does suggest that afternoon exercise may be more beneficial” for people with disrupted metabolisms than the same exercise done earlier.

The study, in Physiological Reports, involved only men, though. Women’s metabolisms might respond differently.

The researchers also did not delve into why the later workouts might affect metabolism differently than earlier ones. But Dr. Schrauwen says he believes moderate afternoon exercise may have an impact on the foods we consume later in the evening and “help to faster metabolize people’s last meals” before they go to sleep. This effect could leave our bodies in a fasted state overnight, which may better synchronize body clocks and metabolisms and fine-tune health.

He and his colleagues hope to explore the underlying molecular effects in future studies, as well as whether the timing of lunch and dinner alters those results. The team also hopes to look into whether evening workouts might amplify the benefits of afternoon exertion, or perhaps undercut them, by worsening sleep.

Ultimately, Dr. Schrauwen says, the particular, most effective exercise regimen for each of us will align “with our daily routines” and exercise inclinations. Because exercise is good for us at any time of day — but only if we opt to keep doing it.

There’s No Easy Fix for Children’s Weight Gain

The Checkup

There’s No Easy Fix for Children’s Weight Gain

Experts advise families to avoid blaming themselves and to look for opportunities to congratulate children for healthy behaviors and good decisions.

Credit…Simone Noronha

  • Jan. 25, 2021, 5:00 a.m. ET

Even when we’re not in the middle of a terrible pandemic, there are a great many tensions around what to say and do at pediatric visits when a child’s weight is increasing too quickly.

There’s the issue of self-image and fat stigma; some people remember forever the moment when a doctor first called their weight a problem, ripping the child out of the happy innocence of feeling comfortable in his or her body.

The pandemic has raised worries about children’s weight gain, perhaps exacerbated by the absence of school, not to mention sports and other activities that used to give structure to the day and mark off some no-eating zones. Economic hardships and curtailed grocery shopping may be limiting some families’ ability to make healthy food choices.

“Parents should allow themselves some grace,” said Dr. Eliana Perrin, professor of pediatrics and director of the Duke Center for Childhood Obesity Research. “Families are having a tough time, kids are having a tough time, there’s increased food insecurity, people have lost their jobs, kids may have lost school meals.”

Dr. Sandy Hassink, a pediatrician who devoted her career to taking care of children with obesity and now works with the American Academy of Pediatrics at the Institute for Healthy Childhood Weight, and who worked on the academy’s interim guidance on obesity, said, “Even in pre-Covid times, I noticed as a clinician that nutrition and activity tend to go out the window in a time of stress.”

[Click here for the recent A.A.P. statement on healthy nutrition and physical activity during the pandemic, and here for its statement on obesity management during the pandemic.]

There are so many factors that have made it more difficult for families to maintain a healthy lifestyle during the pandemic, Dr. Hassink said, from increased sedentary time and screen time to the increased snacking and dysregulated sleep which sometimes come with being at home. Families may have less access to fresh food, she said, and then, of course, there’s stress eating.

Pediatricians often find themselves struggling to find the right balance in what to say to a family in these situations. Somehow, in those fraught moments in the exam room, real or virtual, you have to find words to acknowledge the complexity of the problem but also, most pediatricians feel, to recognize that parents do have some power and some agency, and to offer them hope and encouragement for making at least small adjustments to help the family establish healthier patterns.

Dr. Perrin and her colleagues at Duke pediatrics collected a set of suggestions for families, but before they got to the specifics of dietary change, increased activity, screen time and sleep, they started with a category they called “Survival,” advising families to pay attention to “mind, heart, body, spirit,” to avoid blaming themselves, to look for opportunities to congratulate their children for healthy behaviors and good decisions.

“Forget what ‘needs’ to get done for physical activity goals and ‘perfect’ meal goals,” Dr. Perrin wrote. “Do their best to eat at home and just ‘show up’ every day in terms of physical activity.” Specific suggestions around food include involving children in the cooking, and using the government MyPlate site to plan healthy meals on a budget. For physical activity, find some way to get moving, even a little, every day.

“As always, try to focus on behaviors, not weight,” Dr. Perrin wrote. “What’s important is making sure families are eating as well as they can — whole grains, proteins, fruits and vegetables, drinking water — rather than a ton of fast foods or sugar-sweetened beverages, and making sure they are staying active.”

Among the harshest lessons of this terrible pandemic year has been how health disparities play out across the life course, as we’ve watched higher death and disease rates in Black and brown communities. There are many issues to tackle here in terms of health equity, but for children growing up in at-risk populations, childhood obesity is yet another serious health disparity, linked to some of the underlying conditions that put people at higher risk for severe Covid-19 disease.

These disparities require complex systemic fixes — from access to healthy food, to safe places for outdoor activity, to improved mental health services, to other supports that can reduce stress on families. Instead, parents and children often encounter blame and stigma.

“Obesity itself as a disease presents a risk for more severe Covid infection,” Dr. Hassink said. “If I substituted the word asthma for obesity, people would not be blaming people for having asthma, they would be saying, let’s make sure your environment doesn’t have allergens, let’s make sure you get the right meds, the right medical care, but not blaming the child.”

Dr. Michelle White, an assistant professor of pediatrics at Duke, is a health services researcher who studies what might be protective for families at high risk of obesity, looking at environmental and family factors, including the ways that neighborhoods can contribute to obesity risks — or solutions. “Some families reporting significant impact by Covid-19 are still able to demonstrate resilience to stress and behaviors such as physical activity and healthy diet,” she said. “I think we have a lot to learn from these families.”

Dr. White said it was important not to view pandemic weight gain as a product only of diet and exercise behaviors. “The social context and the physical context of our families is so incredibly important in terms of their risk of weight gain,” she said.

My colleague Dr. Mary Jo Messito, who directs the pediatric weight management program at N.Y.U. School of Medicine and Bellevue Hospital, said, “My patients are suffering terribly.” They face many barriers to exercise because of fears of being exposed to Covid, she said, and also food insecurity and a very high level of stress. “So many people don’t meet their goals because they have unaddressed mental health needs,” Dr. Messito said, pointing to the need for more mental health resources for low-income communities.

“I work to try to give people resources where they are,” she said, offering handouts and information about healthy food for people on limited budgets, but acknowledging, “it’s not going to compete with fast food for calories for dollar.” She recommends in-home exercise programs or talks about how to mask up and go outside safely, and she talks about avoiding sugary drinks.

Dr. Elsie Taveras, a professor of nutrition in the department of pediatrics at Harvard Medical School and the chief of general pediatrics at Massachusetts General Hospital, said that the challenge ahead will be to find ways to “go beyond surface counseling,” to help families find ways to turn this around, perhaps looking for help from experts in mental and behavioral health. Doctors will need to think about the dual burden of weight gain combined with the social risks brought on by the pandemic.

“If a patient with obesity comes in for a visit and I also know the family is living in a motel or they’re food insecure,” she said, “I need to adapt my plan to circumstances rather than say, ‘increase fruits and vegetables.’”

Pandemic weight gain is a problem for adults as well as children, Dr. Taveras said. “We’re home more, have more access to our beds, our refrigerators, our screens, we are experiencing extreme stress and uncertainty, and food and rest are things people turn to for comfort.”

“It’s important for people to have self-compassion here,” Dr. Hassink said. And it’s overwhelming to tackle all of this at once. “Maybe we should be helping people pick one thing they think they could change to make it healthier, strategize about how they might make progress on one thing.”

A parent might try to keep healthier food in the house, thereby eliminating all the individual decisions that have to be made “when your child starts to grab for that unhealthy snack.”

Maybe start by setting a time for a particular meal, she said. Maybe make a deal with a child to stand up and walk around the house for five minutes for every so much screen time.

“Take it one thing at a time that you might want to change, get help from your pediatrician about what resources might be available in your community for food and physical activity, and don’t beat yourself up,” Dr. Hassink said. “Take one small step and then be encouraged to take the next step.”

How the Right Foods May Lead to a Healthier Gut, and Better Health

How the Right Foods May Lead to a Healthier Gut, and Better Health

A diet full of highly processed foods with added sugars and salt promoted gut microbes linked to obesity, heart disease and diabetes.

Credit…Getty Images
Anahad O’Connor

  • Jan. 11, 2021, 11:00 a.m. ET

Scientists know that the trillions of bacteria and other microbes that live in our guts play an important role in health, influencing our risk of developing obesity, heart disease, Type 2 diabetes and a wide range of other conditions. But now a large new international study has found that the composition of these microorganisms, collectively known as our microbiomes, is largely shaped by what we eat.

By analyzing the diets, health and microbiomes of more than a thousand people, researchers found that a diet rich in nutrient-dense, whole foods supported the growth of beneficial microbes that promoted good health. But eating a diet full of highly processed foods with added sugars, salt and other additives had the opposite effect, promoting gut microbes that were linked to worse cardiovascular and metabolic health.

The researchers found that what people ate had a more powerful impact on the makeup of their microbiomes than their genes. They also discovered that a variety of plant and animal foods were linked to a more favorable microbiome.

One critical factor was whether people ate foods that were highly processed or not. People who tended to eat minimally processed foods like vegetables, nuts, eggs and seafood were more likely to harbor beneficial gut bacteria. Consuming large amounts of juices, sweetened beverages, white bread, refined grains, and processed meats, on the other hand, was associated with microbes linked to poor metabolic health.

“It goes back to the age-old message of eating as many whole and unprocessed foods as possible,” said Dr. Sarah E. Berry, a nutrition scientist at King’s College London and a co-author of the new study, which was published Monday in Nature Medicine. “What this research shows for the first time is the link between the quality of the food we’re eating, the quality of our microbiomes and ultimately our health outcomes.”

The findings could one day help doctors and nutritionists prevent or perhaps even treat some diet-related diseases, allowing them to prescribe personalized diets to people based on the unique makeup of their microbiomes and other factors.

Many studies suggest that there is no one-size-fits-all diet that works for everyone. The new study, for example, found that while some foods were generally better for health than others, different people could have wildly different metabolic responses to the same foods, mediated in part by the kinds of microbes residing in their guts.

“What we found in our study was that the same diet in two different individuals does not lead to the same microbiome, and it does not lead to the same metabolic response,” said Dr. Andrew T. Chan, a co-author of the study and a professor of medicine at Harvard Medical School and Massachusetts General Hospital. “There is a lot of variation.”

The new findings stem from an international study of personalized nutrition called Predict, which is the world’s largest research project designed to look at individual responses to food. Started in 2018 by the British epidemiologist Tim Spector, the study has followed over 1,100 mostly healthy adults in the United States and Britain, including hundreds of identical and nonidentical twins.

The researchers collected data on a wide range of factors that influence metabolism and disease risk. They analyzed the participants’ diets, microbiomes and body fat. They took blood samples before and after meals to look at their blood sugar, hormones, cholesterol and inflammation levels. They monitored their sleep and physical activity. And for two weeks they had them wear continuous glucose monitors that tracked their blood sugar responses to different meals.

The researchers were surprised to discover that genetics played only a minor role in shaping a person’s microbiome. Identical twins were found to share just 34 percent of the same gut microbes, while people who were unrelated shared about 30 percent of the same microbes. The composition of each person’s microbiome appeared instead to be driven more by what they ate, and the types of microbes in their guts played a strong role in their metabolic health.

The researchers identified clusters of so-called good gut bugs, which were more common in people who ate a diverse diet rich in high-fiber plants — like spinach, broccoli, tomatoes, nuts and seeds — as well as minimally processed animal foods such as fish and full-fat yogurt. They also found clusters of “bad” gut bugs that were common in people who regularly consumed foods that were highly processed. One common denominator among heavily processed foods is that they tend to contain very little fiber, a macronutrient that helps to nourish good microbes in the gut, the researchers said.

Among the “good” strains of gut microbes were Prevotella copri and Blastocystis, both of which were associated with lower levels of visceral fat, the kind that accumulates around internal organs and that increases the risk of heart disease. These microbes also appeared to improve blood sugar control, an indicator of diabetes risk. Other beneficial microbes were associated with reduced inflammation and lower spikes in blood fat and cholesterol levels after meals, all of which play a role in cardiovascular health.

The new study was funded and supported by Zoe Global, a health science company, as well as by the Wellcome Trust, a British nonprofit, and several public health groups.

Dr. Berry said the findings suggest that by looking at microbiome profiles they can identify people at high risk of developing metabolic diseases and intervene early on. She and her colleagues are now planning a clinical trial that will test whether telling people to change specific foods in their diets can alter levels of good and bad microbes in their guts and subsequently improve their health.

“We think there are lots of small changes that people can make that can have a big impact on their health that might be mediated through the microbiome,” she said.

To Create a Healthy Habit, Find an Accountability Buddy

Well Challenge Day 6

To Create a Healthy Habit, Find an Accountability Buddy

Whether it’s a person or an app that sends us reminders, we make better choices when we’re being watched (even by ourselves.)

Credit…Andrew B Myers
Tara Parker-Pope

  • Jan. 8, 2021, 5:00 a.m. ET

If you want to make positive changes in your life, try building on a lesson many of us learned in 2020: Hold yourself accountable.

The notion of accountability — to yourself and to others — has been an important part of pandemic living. To avoid spreading the virus, we’ve needed to be accountable for wearing a mask, limiting our contacts and keeping our distance.

But accountability can also help you achieve your health goals. Gretchen Rubin, author of “Better Than Before,” a book about forming healthy habits, says that accountability is an important tool for making and breaking habits.

Accountability works best when it comes from the outside. You can create accountability by checking in with a friend every day to talk about healthful eating. You’re more likely to exercise if you’ve made a plan to walk with a friend or scheduled a workout with a personal trainer. You can create public accountability by declaring your intention on social media.

If you prefer to stay accountable only to yourself, you can create accountability by using an app that sends you daily reminders or by wearing a Fitbit or smart watch to track your exercise habits. You can even hold yourself accountable through a daily journal entry.

“We do better when someone’s watching,” Ms. Rubin said. “Even when we’re the ones doing the watching!”

A 2018 North Carolina State University study of 704 people enrolled in a 15-week online weight-loss program found that participants with buddies lost more weight and waist inches than those who took the course without buddy support.

So for today’s Well challenge, think about a health goal you want to achieve and focus on how you can hold yourself accountable. I’ve included a few suggestions for how to do it. Sign up for the Well newsletter to get the 7-Day Well Challenge in your inbox.

Day 6

Create an Accountability Plan

What is your goal for 2021? Do you want to improve your eating habits, lose weight or exercise more? Or maybe you just want to finish that screenplay you’ve been working on? You’re more likely to succeed if you get some help.

Find an accountability buddy. Choose a friend who wants to achieve a similar goal and make a plan. Accountability might mean meeting each other once or twice a week for a walking date. Or it could be a daily text check-in to see how you’re doing on a diet or a Zoom call to work on a decluttering project together.

“Some people are very accountable to themselves, but not most people,” said Dr. Tim Church, a well-known exercise and obesity expert and chief medical officer for Naturally Slim, an app-based behavioral health program in Dallas. “In my years of working with thousands of people, there’s one thing that drives accountability more than anything else: If you want to keep people doing a behavior, get a buddy.”

While the presence of an accountability buddy adds some gentle peer pressure, the key is to focus on the behavior, not success or failure. For instance, if a person is trying to lose weight, don’t focus on the scale. Instead, check in and remind them to log what they ate, encourage them to eat more fruits and vegetables and remind them of the benefits of a regular weigh-in (but you don’t need to ask them the result). If they’re beating themselves up for eating two desserts, talk about what might have triggered an emotional eating binge.

“An accountability partner is there to support you, to problem-solve and to celebrate even the small victories,” Dr. Church said. “Judgment is the quickest way to destroy all that. People are so hard on themselves. You don’t need to be hard on them.”

Use an app. An app is a great way to add accountability to your day. Meditation apps like Headspace and Calm will send daily reminders and track your progress. The weight-loss app Noom asks you to check in for a few minutes each day, complete mini-health courses and track what you’ve eaten. The Fitbit app counts your steps, will sync with your smart scale and vibrates to remind you to get up and move.

Set reminders. Once you set a health goal, hold yourself accountable by creating calendar reminders to help you achieve it. Schedule walk breaks or daily or weekly check-ins with your accountability buddy.

Declare it on social media. Telling your friends on social media that you’re cutting back on packaged foods, or sending a tweet every time you finish a class on your exercise bike creates virtual accountability. Commit to posting on Facebook, Instagram, Twitter or another platform every time you complete a goal, or share your feelings on days you’re struggling. When you declare your goals on social media, you’re likely to find a like-minded friend who will want to join your journey and offer words of support.

Amazon Halo Review: The Fitness Gadget We Don’t Deserve or Need

tech fix

Amazon Halo Review: The Fitness Gadget We Don’t Deserve or Need

The retail giant claims that its health product is extremely precise at scanning body fat. I found otherwise.

Credit…Glenn Harvey
Brian X. Chen

By

  • Dec. 9, 2020, 5:00 a.m. ET

Many of us are in the same boat these days. With the coronavirus killing more people by the day, we are increasingly stress-eating and drinking more alcohol. At the same time, with gyms shut down, we are sitting around more and glued to screens.

So you may be wondering what I’m wondering: How is the pandemic affecting my body? Because we can’t easily leave the house to see doctors for nonemergencies, we are largely left to figure this out on our own.

Enter the Halo, a new fitness-tracking bracelet from Amazon with a novel twist: It claims that by using a smartphone app to scan images of your body, it can tell you how much body fat you have much more precisely than past technologies. The bracelet also has a microphone to listen to your tone of voice and tell you how your mood sounds to other people. (The masochist inside me said, “Sign me up!”)

The Halo is Amazon’s foray into so-called wearable computers that keep an eye on our health, following in the footsteps of Apple and Fitbit. Amazon is selling the Halo for $65 on an invitation-only basis, meaning you have to get on a waiting list to buy it. I volunteered to be a guinea pig and received mine in October.

When the Halo arrived, I installed the app, removed my T-shirt and propped up my phone camera. Here’s what happened next: The Halo said I was fatter than I thought — with 25 percent body fat, which the app said was “too high.”

I was skeptical. I’m a relatively slim person who has put on two pounds since last year. I usually cook healthy meals and do light exercises outdoors. My clothes still fit.

I felt body-shamed and confused by the Halo. So I sent my Halo data and body scans to Dr. Lawrence Cheskin, a professor of nutrition and food studies at George Mason University and founder of the Johns Hopkins Weight Management Center.

After reviewing my results, Dr. Cheskin jotted down my height and weight to calculate my body mass index, which is a metric used to estimate obesity. A man my age (36) with my body mass index, he said, is highly unlikely to have 25 percent body fat.

“Unless you were a couch potato and ate a very poor diet, I have my doubts about the Halo’s diagnosis,” he said.

Dr. Cheskin encouraged me to gather more data by measuring my body fat with other devices, and to do the same with at least one other person. So I did and found that the Halo’s body fat readings consistently skewed higher than other tools for myself and my test subject.

I concluded that the Halo’s body analysis was questionable. More important, it felt like a negative experience that failed to motivate me to get fit. I’ve had much more uplifting experiences with other products like the Apple Watch and Fitbit bands, as laid out below.

Measuring Body Fat

The Amazon Halo bracelet and app.
The Amazon Halo bracelet and app.Credit…Amazon

Body fat measurement can be complicated because the traditional methods available to consumers are not always accurate.

Smart bathroom scales that measure body fat use bioelectrical impedance analysis, which sends a small current through your bare feet. Skin calipers, a more dated method, are essentially rulers that pinch down on skin folds to measure thickness.

These techniques are not perfectly reliable. If people step on smart scales at different times of day or with different levels of hydration, their results may vary. Calipers can measure skin folds incorrectly if you pinch in the wrong areas.

Amazon said the Halo’s technology was much more precise. To scan your body, you use the smartphone’s front-facing camera to take photos of your body from the front, sides and rear. Then Amazon stitches the images together into a 3-D model to analyze your body composition and calculate the percentage of fat.

I decided to record consistent body fat measurements for myself and a friend using the Halo, a Fitbit bathroom scale and a highly rated skin caliper. In November and December, I took early-morning measurements with the Halo and bathroom scale; my wife pinched my skin folds in four areas with the caliper. I measured my test subject’s body fat once with each device.

Our results were remarkably similar for two men with very different body compositions:

  • The Amazon product estimated that my friend, a 6-foot-3 man weighing 198 pounds, had 24 percent body fat, the Fitbit scale read 19 percent, and the skin-fold measurements added up to 20 percent.

  • For myself — 5-foot-6 and about 140 pounds — the Halo said in November that I had 25 percent body fat, the Fitbit scale said 19 percent, and the skin-fold measurements added up to 20 percent. In December, the Halo said I had 26 percent body fat (alas, I had more Thanksgiving leftovers than usual), the Fitbit scale said 20 percent, and the skin-fold measurements added up to 21 percent.

Dr. Cheskin speculated that the Halo might have an overestimating bias in its algorithm because underestimating body fat for an obese person would be more problematic.

Dr. Maulik Majmudar, Amazon’s medical officer, who worked on the Halo, said people should expect the device’s results to be different because the method was more accurate than body fat scales and calipers.

Amazon developed its body-measuring algorithm from a sample set of tens of thousands of images of people’s bodies from across a wide range of demographics, he said. Amazon then did internal tests measuring people’s body fat using the Halo scanner, smart bathroom scales and DEXA, a technique that uses X-rays to scan for bone density, which studies have found to be a reliable measure for body fat. It found that the Halo method was twice as accurate as bathroom scales.

Still, Dr. Cheskin was unconvinced by Amazon’s accuracy claims. He said a valid study would involve a clinical trial measuring body fat of many human subjects with each method — the Halo, DEXA, bioelectrical impedance scales and calipers — and comparing the results side by side.

Accurate or not, the most disappointing part of Amazon’s body fat analysis was that it lacked important context. Even though the app asked for my ethnicity, age and sex, it said my 25 percent body fat level was too high and well outside the “Healthy” zone (roughly 12 to 18 percent). It also said healthy results were associated with longer life and lower risks of heart disease.

Dr. Cheskin offered a more nuanced analysis. Body fat levels may have different health implications depending on your age, ethnicity, sex, cholesterol levels and family history. Waist circumference matters, too, because severe abdominal fat can be associated with health problems.

For an Asian man my age with a 34-inch waistline, whose family has not had a history of diabetes or heart problems, and whose blood tests recently showed normal cholesterol levels, even a 25 percent body fat reading would probably not be alarming, he said.

That context, combined with my body mass index along with the measurements taken with a body fat scale and caliper, led Dr. Cheskin to doubt Halo’s analysis.

He worried about the technology’s potential consequences.

“Does it potentially create eating disorders?” he said. “You’re taking a bunch of people with normal weight and B.M.I. and telling them they’re too fatty. What are they going to do with that? Some of them are going to be more compulsive and start doing things that are going to be inappropriate.”

Bottom Line

This experiment raised another question: What in the world was Amazon thinking releasing a product like this now? It has been impossible for us to move around as much as we used to this year. If anything, we should accept that our bodies will be imperfect during this time.

Dr. Majmudar said he felt the opposite. As a clinician, he said, he would encourage patients to mitigate the health risks of gaining weight and being more sedentary in the pandemic. The goal of the Halo was to drive behavioral change with education and awareness, he said.

“The desire or intention was never to body-shame people,” he added.

In my experience, there are better fitness-tracking products that offer more positive motivation.

The Apple Watch, for one, lets you set goals for how much you want to move or exercise each day, and those goals are symbolized by colorful rings that are shown on the watch face. Once a ring is completed, you have met your goal. Fitbit devices send notifications to your phone, egging you on when you are nearing your step goal. Neither device comes anywhere close to giving you body dysmorphia.

Another of Halo’s unique features is Tone, which uses the bracelet’s microphone to periodically eavesdrop on your conversations to tell you what your mood sounds like. I turned the feature off after two days because it felt like a creepy invasion of privacy. But I left it on long enough to complain to my wife about what a bad idea it was.

After analyzing the conversation, the Halo app said I sounded irritated and disgusted. That, at least, was accurate.

Yes, Many of Us Are Stress-Eating and Gaining Weight in the Pandemic

Yes, Many of Us Are Stress-Eating and Gaining Weight in the Pandemic

A global study confirms that during the pandemic, many of us ate more junk food, exercised less, were more anxious and got less sleep.

Credit…Lorenzo Gritti
Anahad O’Connor

By

  • Dec. 4, 2020, 5:00 a.m. ET

Not long ago, Stephen Loy had a lot of healthy habits. He went to exercise classes three or four times a week, cooked nutritious dinners for his family, and snacked on healthy foods like hummus and bell peppers.

But that all changed when the pandemic struck. During the lockdowns, when he was stuck at home, his anxiety levels went up. He stopped exercising and started stress eating. Gone were the hummus and vegetables; instead, he snacked on cookies, sweets and Lay’s potato chips. He ate more fried foods and ordered takeout from local restaurants.

“We were feeding the soul more than feeding the stomach,” said Mr. Loy, 49, who lives in Baton Rouge and is the executive director of a tech incubator. “We were making sure to eat things that made us feel better — not just nutritional items.”

Now a global survey conducted earlier this year confirms what Mr. Loy and many others experienced firsthand: The coronavirus pandemic and resulting lockdowns led to dramatic changes in health behaviors, prompting people around the world to cut back on physical activity and eat more junk foods. It drove anxiety levels higher and disrupted sleep. And those who are obese, who already face increased health risks, may have fared the worst, the researchers found. While they tended to experience improvements in some aspects of their diets, such as cooking at home more and eating out less, they were also the most likely to report struggling with their weight and mental health.

The findings, published in the journal Obesity, offer a cautionary lesson for many of us as coronavirus cases continue to surge and renewed calls for lockdowns and other restrictions again take hold. With months to go before a vaccine becomes widely available and we can safely resume our pre-pandemic routines, now might be a good time to assess the healthy habits we may have let slip and to find new ways to be proactive about our physical and mental health.

The study, carried out by researchers at the Pennington Biomedical Research Center in Louisiana, surveyed almost 8,000 adults across the globe, including people from 50 different countries and every state in America. The researchers found that the decline in healthy behaviors during the pandemic and widespread lockdowns was fairly common regardless of geography.

“Individuals with obesity were impacted the most — and that’s what we were afraid of,” said Emily Flanagan, an author of the study and postdoctoral fellow at the Pennington Biomedical Research Center. “They not only started off with higher anxiety levels before the pandemic, but they also had the largest increase in anxiety levels throughout the pandemic.”

The findings shed light on exactly how people altered their routines and behaviors in response to the lockdowns that were implemented in countries around the world this year to slow the spread of the virus. The pandemic disrupted everyday life, isolated people from friends and family, and spawned an economic crisis, with tens of millions of people losing jobs or finding their incomes sharply reduced.

Dr. Flanagan and her colleagues assumed many people were experiencing enormous levels of stress. But they were not sure how the pandemic and stay-at-home orders were impacting how people slept, how much they exercised and what they ate. So they designed an extensive survey and recruited people on social media to answer questions about how their mental and physical health had been affected.

“This was such a drastic and abrupt change to everyone’s daily life that we needed to see what was going on,” said Dr. Flanagan. “We wanted to put some data to the anecdotal behaviors we were seeing.”

From April through early May, about 7,750 people, most of them from the United States but also from countries such as Canada, Australia and Britain, completed the survey. The average age of the respondents was 51, and a majority were women. Based on their body mass indexes, about a third of the people were overweight, a third were obese, and a third were considered normal weight.

The researchers found that most people became more sedentary, which they said was probably related to less daily commuting and more time spent indoors. But even when people did engage in structured exercise, it tended to be at lower intensity levels compared to before the pandemic. Many people also said they had given in to their food cravings: Consumption of sugar sweetened beverages and other sugary snack foods, for example, went up.

That might explain another finding: About 27 percent of people said they had gained weight after the initial lockdowns went into effect. The figure was even higher among people classified as obese: About 33 percent said that they had gained weight, compared to 24.7 percent of people considered normal weight. People who gained weight also had the largest declines in physical activity.

There were some bright spots in the findings. About 17 percent of the study population actually lost weight during the pandemic; perhaps not surprisingly, they tended to be people who increased their physical activity levels and improved their diets. And despite snacking on more junk foods, many people showed an increase in their “healthy eating scores,” a measure of their overall diet quality, which includes things like eating more fruits and fewer fried foods. The researchers said that the overall improvements in diet appeared to be driven by the fact that the lockdowns prompted people to cook, bake and prepare more food at home. Other recent surveys have also shown a sharp rise in home cooking and baking this year, with many people saying they are discovering new ingredients and looking for ways to make healthier foods.

But social isolation can take a toll on mental wellness, and that was evident in the findings. On average, people reported significantly higher anxiety levels. About 20 percent said that their symptoms, such as experiencing dread and not being able to control or stop their worrying, were severe enough to interfere with their daily activities. About 44 percent of people said that their sleep had also worsened during the pandemic. People on average reported going to bed about an hour later than usual and waking up roughly an hour later than usual. Only 10 percent of people said that their sleep had improved since the pandemic began.

The greatest spikes in anxiety occurred among people who are obese. It was unclear why exactly, but one reason may have been concerns about the virus. The survey took place at a time when studies were first beginning to show that excess weight puts people at a much higher risk of being hospitalized with Covid-19. “We don’t have data to back this up, but our hypothesis is there was a lot more anxiety about their own health,” Dr. Flanagan said. “A heightened fear of the virus would most certainly increase their anxiety levels.”

Dr. Flanagan said it was perhaps not surprising that people tended to engage in less healthful habits during the pandemic, as so many aspects of health are intertwined. Stress can lead to poor sleep, which can cause people to exercise less, consume more junk foods, and then gain weight, and so on. But she said she hoped that the findings might inspire people to take steps to be more proactive about their health, such as seeking out mental health specialists, prioritizing sleep and finding ways to exercise at home and cook more, in the event of future lockdowns.

“Being aware of how our health behaviors change during these stay-at-home orders could help us combat that if another lockdown is enforced,” she said. “Being aware is really the No. 1 thing here.”

How Exercise Changes Our Blood

While we exercise, we raise and lower the levels of hundreds of molecules in our bloodstreams that are related to our metabolic health, even if we work out for only a few minutes, according to a complex and encouraging new study of the molecular effects of being active. The study, which involved more than 1,000 men and women, adds to growing evidence that exercise improves our health in large part by transforming the numbers and types of cells inside of us.

There is at this point, of course, no reasonable debate about whether exercise is good for us. It is. Countless studies show that people who are active are less likely than more-sedentary people to develop or die from a host of health problems, including heart disease, diabetes, dementia, cancer, obesity and many others. Active people also tend to live longer and feel happier.

But we still know surprisingly little about just how exercise changes us for the better. What are the many, interconnected biological steps and transmutations that allow a walk today to add to our life span decades from now?

That question has been driving considerable interest recently in research looking at exercise “omics” — the study of all of the molecules in our blood or other tissues that are part of a particular biological process. Genomics, for instance, quantifies the many, many molecules involved in genetic activities. Proteomics does the same for proteins, microbiomics for the multiple contents of our microbiomes and metabolomics for molecules related to metabolic processes. (There can be overlap between various ’omics, obviously.)

Understanding how exercise affects the levels of the various molecules within us is important, because these changes are likely to be the preliminary step in a complex cascade of further biological actions that contribute to better health. Increase some molecules, decrease others, and you jump-start inter-organ messaging, gene expression and other processes that subsequently alter how we make and use insulin, burn or store fat, respond to cholesterol and so on.

A number of important recent studies have delved into the ’omics of exercise, including a fascinating experiment showing that a short workout rapidly changes the levels of 9,815 molecules in people’s bloodstreams. But that study, like most other examinations of exercise and ’omics, involved relatively few volunteers — 36, in that case — and did not link molecular changes with subsequent health outcomes.

So, for the new study, which was published in September in Circulation, researchers at Massachusetts General Hospital in Boston and other institutions decided to up the number of exercisers whose ’omics would be parsed and also try to find connections between the ’omics data and later health.

Conveniently, they had access to a large group of potential volunteers among men and women already enrolled in the long-term Framingham Heart Study, which is overseen primarily by researchers at Massachusetts General Hospital. The scientists now asked 411 middle-aged volunteers enrolled in the study to visit the lab and exercise, by pedaling to exhaustion on a stationary bicycle. Most riders’ efforts lasted for a little less than 12 minutes. The researchers drew blood before the ride and afterward, within about a minute of when, worn out, the cyclists quit.

The scientists then ran the blood samples through a mass spectrometer, a machine that counts and quantifies molecules. The researchers focused on metabolites, which are molecules related to metabolic processes. The label “metabolite” is somewhat arbitrary, but for this study, the researchers focused mostly on molecules that could affect people’s insulin, fat burning, cholesterol, blood sugar and other aspects of cellular fueling.

They found plenty. Of 588 metabolites checked, the levels of more than 80 percent generally grew or dropped during the short rides. To reinforce those findings, the scientists repeated the experiment with another 783 Framingham volunteers, checking their blood before and after exercise for changes in about 200 of the molecules that had been most altered in the first group. Again, these metabolites changed in the same ways as before.

Last and perhaps most intriguing, the researchers created what they called molecular “signatures” of the levels of a few, representative metabolites that changed with exercise. They then looked for these same patterns of metabolites in stored blood samples gathered decades before from past Framingham participants, while also checking to see if and when any of these volunteers had passed away.

The relevant signatures popped up in some of the blood samples, the researchers found, and these samples tended to be from people who had not died prematurely, suggesting that the kinds of metabolite changes that occur with exercise might influence and improve health well into the future.

That idea is “speculative,” though, says Dr. Gregory Lewis, the section head of the heart failure program and director of the cardiopulmonary exercise laboratory at Massachusetts General Hospital, who oversaw the new study. The decades-old blood samples were drawn during standard medical testing, not after exercise, he says, so some people with desirable metabolite signatures might have been born that way and not needed workouts to remodel their metabolites.

Even among the current volunteers, he points out, different people’s molecules responded somewhat differently to their exercise. Over all, people with obesity developed fewer changes than leaner riders, suggesting they might somehow resist some of the benefits of exercise. Men and women, as groups, also showed slightly discordant molecular signatures, but age did not influence people’s molecular responses.

Larger future ’omics studies should help scientists tease out how and why we each react as we do to exercise, Dr. Lewis says, and enable researchers to define more-precise molecular signatures that might indicate, with a blood test, how fit someone is or how their bodies may respond to different types of exercise.

But for now, the current study underscores just how pervasive and immediate the effects of exercise can be. “This was barely 10 minutes of exercise,” Dr. Lewis says, “but it shifted so much” inside people.

Weight Has Greater Impact on Diabetes Than Heart Disease

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Carrying excess weight may have a greater impact on the risk for diabetes than it does on the risk for heart disease or early death, a new study has found.

To look at the effect of obesity independent of genetics, Swedish researchers followed 4,046 pairs of identical twins whose average age was 58. One of the twins was overweight, and the other was not. Since identical twins have the same genes, their weight difference could not be attributed to genetics. The study is in JAMA Internal Medicine.

After accounting for physical activity, smoking and educational level, the researchers found that having a higher body mass index, or B.M.I. — even among those in the obese range of 30 or higher — was not associated with an increased risk for heart attack or death. But a high B.M.I. was associated with an increased risk for diabetes.

“Based on these results, the association between obesity and cardiovascular disease is explained by genetic, not environmental, factors,” said the lead author, Peter Nordstrom, a professor of geriatric medicine at Umea University. “Unfortunately, this also means that environmental factors that reduce obesity do not reduce the risk of cardiovascular disease or death. But they most certainly decrease the risk for diabetes.”

Cutting Sugar Rapidly Improves Heart Health Markers

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Obese children who cut sugar from their diets saw improvements in markers of heart disease after just nine days, a study in Atherosclerosis found.

For the study, researchers evaluated 37 children ages 9 to 18 who were obese and at high risk for heart disease and Type 2 diabetes. The children were given food and drinks totaling the same number of calories, fat, protein and carbohydrates as their typical diets.

The only change was their sugar intake: The researchers swapped foods high in added sugars, like pastries and sweetened yogurts, for options like bagels and pizza. This lowered dietary sugar from 28 percent to 10 percent, and fructose from 12 percent to 4 percent of total calories.

After nine days, the researchers found a 33 percent drop in triglycerides, a type of fat tied to heart disease; a 49 percent reduction in a protein called apoC-III that is tied to high triglyceride levels; and dramatic reductions in small, dense LDL cholesterol, a risk factor for heart disease.

Though this study is small and short-term, it builds on this group’s previous research implicating added sugars as a contributor to metabolic disorders and heart disease.

“Sugar calories are not like other carbohydrate calories,” said Dr. Robert Lustig, a co-author of the study and professor of pediatrics at Benioff Children’s Hospital at the University of California, San Francisco. “Without changing total carbohydrate, or fat, or protein, we were able to accomplish this enormous improvement in their cardiovascular risk factors,” unrelated to weight loss, he said.

An Early Bedtime for Kids May Fight Weight Gain

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Preschool children who are in bed by 8 p.m. are far less likely to be obese during adolescence than children who stay up late, a study has found. Their risk of teenage obesity is half the risk faced by preschoolers who stay up past 9 p.m.

The research analyzed data gathered on nearly 1,000 children born in 1991 whose bedtimes were recorded when they were 4½ years old, and whose height and weight were recorded at age 15. The children were part of the Study of Early Child Care and Youth Development, done under the auspices of the National Institute of Health’s Eunice Kennedy Shriver National Institute of Child Health and Human Development.

Among the children who were in bed by 8 p.m., 10 percent were obese as teens, compared to 16 percent of those who went to bed between 8 and 9 and 23 percent of those who went to bed after 9, according to the study, published in The Journal of Pediatrics.

The researchers adjusted for such factors as socioeconomic status, maternal obesity and parenting style and still found that the children who went to bed by 8 p.m. were at less than half the risk of teenage obesity as those who were up past 9, said Sarah E. Anderson, the paper’s lead author and an associate professor of epidemiology at the Ohio State University College of Public Health in Columbus.

Although the study does not prove that early bedtimes protect against obesity, Dr. Anderson said, “there is a great deal of evidence linking poor sleep, and particularly short sleep duration, to obesity, and it’s possible the timing of sleep may be important, above and beyond the duration of sleep.”

“This provides more evidence that having an early regular bedtime and bedtime routine for young children is helpful,” she said.

To Stem Obesity, Start Before Birth

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Credit Paul Rogers

To stem the current epidemic of obesity, there’s no arguing with the adage that an ounce of prevention is worth a pound of cure. As every overweight adult knows too well, shedding excess pounds and keeping them off is far harder than putting them on in the first place.

But assuring a leaner, healthier younger generation may often require starting even before a baby is born.

The overwhelming majority of babies are lean at birth, but by the time they reach kindergarten, many have acquired excess body fat that sets the stage for a lifelong weight problem.

Recent studies indicate that the reason so many American children become overweight is far more complicated than consuming more calories than they burn, although this is certainly an important factor. Rather, preventing children from acquiring excess body fat may have to start even before their mothers become pregnant.

Researchers are tracing the origins of being overweight and obese as far back as the pre-pregnancy weight of a child’s mother and father, and their explanations go beyond simple genetic inheritance. Twenty-three genes are known to increase the risk of becoming obese. These genes can act very early in development to accelerate weight gain in infancy and during middle childhood.

In the usual weight trajectory, children are born lean, get chubby during infancy, then become lean again as toddlers when they grow taller and become more active. Then, at or before age 10 or so, body fat increases in preparation for puberty – a phenomenon called adiposity rebound.

In children with obesity genes, “adiposity rebound occurs earlier and higher,” said Dr. Daniel W. Belsky, an epidemiologist at Duke University School of Medicine. “They stop getting leaner sooner and start putting on fat earlier and put on more of it.”

Still, twin and family studies have shown that many children with these genes remain lean. Furthermore, these same genes were undoubtedly around in the 1960s and 1970s when the obesity rate in children was a fraction of what it is today.

So what is different about the 2000s? Children today are surrounded by a surfeit of unwholesome, easy-to-consume calorie-dense foods and snacks accompanied by a deficit of opportunities to expend those extra calories through regular physical activity. And countering a calorie-rich, sedentary environment is now harder than it should be, with the current heavy emphasis on academics, parental reluctance to let children play outside unattended, and intense competition from electronics. All these circumstances may give obesity genes a greater chance to express themselves.

“There is no going back to a world in which calories are scarce and obtaining them is physically demanding,” Dr. Belsky wrote in an editorial in JAMA Pediatrics. “And governments and their publics have shown little enthusiasm for regulations restricting access to palatable, calorie-dense foods.”

Curbing consumption of sugar-sweetened beverages and keeping calorie-dense junk food out of the house and other settings where young children spend time is crucial. This is especially important for infants and children with large appetites that are not easily satisfied.

It’s also essential that parents model good eating habits, experts agree. “If you do it, they’ll do it,” David S. Ludwig, an obesity specialist at Children’s Hospital Boston, said. “Young children are like ducklings, they want to do what their mothers do.”

Equally important, Dr. Belsky said, is “allowing children in institutional settings – in day care, preschool and elementary school – to be as active as they choose to be rather than forcing them to sit quietly in chairs most of the day. Being physically active encourages a healthy metabolism. Active children are not constantly hungry.”

He added, “In the face of the obesity epidemic, eliminating the handful of opportunities for kids to be active during the day is a shame. Sedentary behavior becomes a life pattern.”

Another critical issue is the vicious cycle of overweight that starts with future mothers and fathers who are overweight or obese. “If we want healthy kids, we need healthy moms before pregnancy and during pregnancy,” Dr. Belsky said. “There are multiple pathways by which unhealthy levels of weight before and during pregnancy can influence a child’s weight going forward.”

As Dr. Ludwig explained, “Although genes are not modifiable, the weight of the mother before and during pregnancy is. Excessive weight gain during pregnancy predicts not just the baby’s birth weight but also the likelihood of obesity in middle childhood.”

The father’s weight is also turning out to be important, Dr. Ludwig said. “Acquired factors influence gene expression,” he said. “Being heavy alters DNA in the father’s sperm that changes gene expression and can be passed down to the next generation.”

Most, though not all, studies have linked a longer duration of breast-feeding to a reduced risk of overweight in children. Although Dr. Ludwig said that the effect “is not dramatic,” a more important benefit of breast-feeding may be “exposing the baby to a wider range of tastes based on what a mother is eating. If a breast-feeding mom eats a large variety of nutritious foods, the child is more likely to like them.”

Antibiotics given early in life, however, may counter any potential benefits of breast-feeding for weight gain, a new study found. Researchers at the University of Helsinki in Finland reported that when breast-fed infants are treated with antibiotics, the antibiotics kill off health-promoting bacteria that live in the gut. “The protective effects of breast-feeding against infections and overweight were weakened or completely eliminated by early-life antibiotic use,” the team wrote in JAMA Pediatrics last month.

Even if children have already started on a path of poor eating habits and excess weight gain, Dr. Ludwig said it is not too late to make healthful changes. As founder of the Optimal Weight for Life program and author of “Ending the Food Fight: Guide Your Child to a Healthy Weight in a Fast Food/Fake Food World,” he advocates an authoritative, but not an authoritarian, parenting style that eliminates stress and conflict over what and when a child eats.

“Never force food on a child,” he insists. “Stand your ground in a gentle but firm way and be prepared to do a little negotiating. When a child refuses to eat the dinner that’s served, put it away in the fridge to be eaten later. If the child says ‘I’m not going to eat it,’ the response should be, ‘Fine, just go to bed,’ not ‘O.K., I’ll make you mac and cheese.’

“Children should be allowed to control their bodies, but parents have to provide the guidance and control the environment,” Dr. Ludwig said.

This is the second of two columns on childhood obesity. Read the first: “The Urgency in Fighting Childhood Obesity.”

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The Urgency in Fighting Childhood Obesity

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Credit Paul Rogers

Life-threatening ailments like heart disease, cancer, stroke and Type 2 diabetes most often afflict adults. But they are often consequences of childhood obesity.

Two new studies, conducted among more than half a million children in Denmark who were followed for many years, linked a high body mass index in children to an increased risk of developing colon cancer and suffering an early stroke as adults. The studies, presented at the European Obesity Summit in Gothenburg, Sweden, this spring, underscore the importance of preventing and reversing undue weight gain in young children and teenagers.

One study, of more than 257,623 people, by Dr. Britt Wang Jensen and colleagues at the Institute of Preventive Medicine, in Bispebjerg, Denmark, and Frederiksberg Hospital in Copenhagen, grouped children according to standard deviations from a mean B.M.I., adjusted for a child’s age and sex.

They found that each unit of increase in being overweight at age 13, generally corresponding to a two- to three-point increase in B.M.I., increased the risk of developing colon cancer by 9 percent and rectal cancer by 11 percent.

The second study, involving 307,677 Danish people born from 1930 to 1987, used a similar grouping of B.M.I. The risk of developing a clot-related stroke in early adult life increased by 26 percent in women and 21 percent in men for each unit of increase in being overweight at all stages of childhood, but especially at age 13.

Although neither study proves that excess weight in childhood itself, as opposed to being overweight as an adult, is responsible for the higher rates of cancer and stroke, overweight children are much more likely to become overweight adults — unless they adopt and maintain healthier patterns of eating and exercise.

According to the American Academy of Child and Adolescent Psychiatry, obesity most often develops from ages 5 to 6 or during the teen years, and “studies have shown that a child who is obese between the ages of 10 and 13 has an 80 percent chance of becoming an obese adult.”

In a study published in 2014 in The New England Journal of Medicine, Solveig A. Cunningham and colleagues at Emory University found that “overweight 5-year-olds were four times as likely as normal-weight children to become obese by age 14.” The study, which involved a representative sample of 7,738 kindergartners, found that the risk of becoming obese did not differ by socioeconomic status, race or ethnic group, or birth weight. Rather, it showed that excess weight gain early in life is a risk factor for obesity later in childhood across the entire population.

Children are generally considered obese when their B.M.I. is at or above the 95th percentile for others of the same age and sex. Currently, about one-third of American children are overweight or obese. By 2012, the Centers for Disease Control and Prevention reports, 18 percent of children and 21 percent of adolescents were obese.

The adverse effects of excess weight in childhood and adolescence don’t necessarily wait to show up later in life. In a review of complications resulting from youthful obesity, Dr. Stephen R. Daniels, a pediatrician at the University of Colorado School of Medicine and the Children’s Hospital in Denver, found that problems in many organ systems were often apparent long before adulthood. They include high blood pressure; insulin resistance and Type 2 diabetes; high blood levels of heart-damaging triglycerides and low levels of protective high-density lipoprotein (HDL) cholesterol; nonalcoholic fatty liver disease; obstructive sleep apnea; asthma; and excess stress on the musculoskeletal system resulting in abnormal bone development, knee and hip pain, and difficulty walking.

Problems of youthful obesity go beyond physical ones. Obese adolescents have higher rates of depression, which in itself may foster poor eating and exercise patterns that add to their weight problem and result in a poor quality of life that persists into adulthood.

In a study conducted in Singapore, researchers reported that “individuals who were obese in childhood are more likely to have poor body image and low self-esteem and confidence, even more so than those with adult onset obesity.”

Another study by Dr. Jeffrey B. Schwimmer of the University of California, San Diego, and colleagues found that obese children and adolescents reported a diminished quality of life that was comparable to that of children with cancer.

Taken together, the data speak to the critical importance of preventing undue weight gain in young children, a task that depends largely on parents, who are responsible for what and how much children eat and how much physical activity they engage in. As researchers from the University Medical Center Groningen in the Netherlands put it, “Early recognition of overweight or obesity in children by their parents is of utmost importance, allowing interventions to start at a young age.” Yet, they found in a study of the parents of 2,203 5-year-olds, “parents underestimated their overweight child in 85 percent of the cases.”

Though it seems logical that parents who think their children are overweight would make a special effort to assure they would “grow into” their weight as they get older, research has shown the opposite. Such children tend to get even fatter, according to findings from the Longitudinal Study of Australian Children reported in April in the journal Pediatrics by Eric Robinson of the University of Liverpool and Angelina R. Sutin of Florida State University College of Medicine.

Even being labeled overweight can itself be damaging and make it harder for children to avoid bad habits, the authors suggested. A 2014 study of girls aged 10 to 19 found that “regardless of actual weight, adolescents who reported having been labeled ‘too fat’ by a family member or peer were more likely to become obese nearly a decade later.”

“I encourage parents to change the environment at home,” Dr. Daniels of the University of Colorado said in an interview. “Without being authoritarian, they should limit high-calorie-dense foods, keep sugar-sweetened beverages out of the house and assure that kids eat the right amount of fruits and vegetables and fewer calorie-dense snacks. Parents also need to be tuned into opportunities for physical activity and set hard-and-fast rules about television and time spent on electronics.”

Following the “5210” daily program endorsed by the American Academy of Pediatrics can help: Aim for five fruits and vegetables a day; keep recreational screen time to two hours or less; include at least one hour of active play: and skip sugar-sweetened beverages and drink water.

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Putting Breast Cancer on a Diet

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Linda Guinee, 60, a survivor of breast cancer, particpated in an earlier trial to see if weight-loss could improve her outcome. She lost 15 pounds and increase her physical activity.

Linda Guinee, 60, a survivor of breast cancer, particpated in an earlier trial to see if weight-loss could improve her outcome. She lost 15 pounds and increase her physical activity.Credit Shiho Fukada for The New York Times

Should weight loss be prescribed as a treatment for breast cancer?

Scientists are recruiting thousands of women for a large clinical trial to find out. The plan is to put heavy women age 18 and older who were recently given diagnoses of breast cancer on diets to see if losing weight will keep their cancer from coming back.

“We have been telling women to do this for years, but we don’t really have definitive proof,” said Dr. Jennifer Ligibel, the principal investigator of the Breast Cancer Weight Loss study, who is a breast oncologist in the Susan F. Smith Center for Women’s Cancers at Dana-Farber Cancer Institute in Boston.

“If it shows that losing weight by increasing physical activity and reducing calories improves survival, weight loss and physical activity could become a standard part of treatment for millions of breast cancer patients around the world,” Dr. Ligibel said.

In a sense, the clinical trial is long overdue. Once a woman is given a breast cancer diagnosis, obesity is associated with a higher risk for recurrence and lower likelihood of survival in women of all ages, Dr. Ligibel said.

Studies showing that obese and overweight women are more likely to die of their breast cancer date back decades. Just two years ago, a meta-analysis crunched the numbers from more than 80 studies involving more than 200,000 women with breast cancer, and reported that women who were obese when diagnosed had a 41 percent greater risk of death, while women who were overweight but whose body mass index was under 30 had a 7 percent greater risk.

But while those studies showed an association between weight and breast cancer mortality, they weren’t designed to find out if weight loss after diagnosis improves survival or reduces the chance of a recurrence.

“Nobody understands biologically why that is,” Dr. Ligibel said, adding that researchers will be collecting blood samples throughout the trial to track metabolic changes that occur with weight loss. Exercise is also part of the program, and participants will work with health coaches. Fitbit is donating all the products that will be used to track their activity and weight.

The researchers will look at markers of inflammation and metabolism, including levels of insulin, insulinlike growth factor and hormones that regulate fat storage.

“There’s a physiology of obesity that happens in everybody, but many of the changes we see in obesity actually are factors that influence the growth of cancer,” said Dr. Pamela Goodwin, one of the study’s investigators and a professor of medicine at Mount Sinai Hospital in Toronto.

These changes include higher insulin and glucose levels, inflammation and an increase in certain proteins, all of which appear to fuel cancer growth, Dr. Goodwin said.

Obesity “makes a great environment for cancer to get a foothold and progress,” said Barbara Gower, a professor of nutrition at the University of Alabama at Birmingham, who is running a small short-term trial to see what happens when women with ovarian cancer remove all sugar and starches from their diet. “The hormonal messages getting through to cancer cells are that it’s a good time to grow, and the nutrition they need is there, too.”

While a drug may target one of the factors, Dr. Ligibel said, weight loss and exercise may be a more powerful intervention because they lead to a combination of changes. “You have something that can potentially change all of them to a metabolically healthy low inflammatory state,” Dr. Ligibel said.

The trial, which will get underway this summer, will cost an estimated $15 million to $20 million. It’s sponsored by the National Cancer Institute and the Alliance for Clinical Trials in Oncology.

Researchers are recruiting 3,200 women from across the United States and Canada who have a recent diagnosis of Stage 2 or Stage 3 breast cancer. Participants must be overweight, with a body mass index of at least 27, and have hormone receptor positive or triple negative tumors. (Women with another type of breast cancer, known as HER2-positive, will not be included because their prognosis does not appear to be associated with weight, researchers said.)

Participants must be 18 but there is no upper age limit, though they must be able to walk “a couple of city blocks and have a life expectancy of at least five years for other causes,” Dr. Ligibel said.

Volunteers will be randomly assigned to either a telephone-based weight loss program or to a control group for comparison. The goal for those in the intervention is to lose 10 percent of their body weight over two years. Participants will continue to be followed for 10 years to see whether their cancer progresses or not.

Weight loss is challenging, and some cancer treatments cause weight gain. But an earlier trial that tested a similar telephone-based weight loss intervention on a smaller scale found that women with breast cancer lost 4 to 5 percent of their body weight, Dr. Goodwin said.

“Breast cancer is a teachable moment,” she added.

The new trial might help doctors identify which patients will benefit most from losing weight, and whether even moderate weight loss is helpful, said Dr. Clifford Hudis, the new chief executive officer of the American Society of Clinical Oncology and former chief of Memorial Sloan Kettering Cancer Center’s breast medicine service, who was involved in the design of the Breast Cancer Weight Loss trial.

“If I tell patients they need to lose 20 pounds, they just roll their eyes and say it’s impossible,” Dr. Hudis said. “But if we could say they only need to lose 3 percent of their body weight, that wouldn’t be so scary. That’s more manageable.”

Parents Should Avoid Comments on a Child’s Weight

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Credit Stuart Bradford

Should parents talk to an overweight child about weight? Or should they just keep their mouths shut?

Parents in this situation are understandably torn. Say something, and they risk shaming a child or worse, triggering an eating disorder. Say nothing, and they worry they’re missing an opportunity to help their child with what could become a serious long-term health problem.

Now a new study offers some guidance: Don’t make comments about a child’s weight.

The study, published in the journal Eating & Weight Disorders, is one of many finding that parents’ careless — though usually well-meaning — comments about a child’s weight are often predictors of unhealthy dieting behaviors, binge eating and other eating disorders, and may inadvertently reinforce negative stereotypes about weight that children internalize. A parent’s comments on a daughter’s weight can have repercussions for years afterward, contributing to a young woman’s chronic dissatisfaction with her body – even if she is not overweight.

“Parents who have a child who’s identified as having obesity may be worried, but the way those concerns are discussed and communicated can be really damaging,” said Rebecca Puhl, deputy director of the Rudd Center for Food Policy and Obesity at the University of Connecticut. “The longitudinal research shows it can have a lasting impact.”

The impact on girls may be especially destructive, she said, because “girls are exposed to so many messages about thinness and body weight, and oftentimes women’s value is closely linked to their appearance. If parents don’t challenge those messages, they can be internalized.”

The new study included over 500 women in their 20s and early 30s who were asked questions about their body image and also asked to recall how often their parents commented about their weight. Whether the young women were overweight or not, those who recalled parents’ comments were much more likely to think they needed to lose 10 or 20 pounds, even when they weren’t overweight.

The study’s lead author, Dr. Brian Wansink, a professor and the director of Cornell University’s Food and Brand Lab, characterized the parents’ critical comments as having a “scarring influence.”

“We asked the women to recall how frequently parents commented, but the telling thing was that if they recalled it happening at all, it had as bad an influence as if it happened all the time,” said Dr. Wansink, author of the book “Slim by Design.” “A few comments were the same as commenting all the time. It seems to make a profound impression.”

Some studies have actually linked parents’ critical comments to an increased risk of obesity. One large government-funded study that followed thousands of 10-year-old girls found that, at the start of the study, nearly 60 percent of the girls said someone — a parent, sibling, teacher or peer – had told them they were “too fat.” By age 19, those who had been labeled “too fat” were more likely to be obese, regardless of whether they were heavy at age 10 or not.

Comments made by family members had even stronger effects than comments made by unrelated people.

Several studies have found that when parents encourage overweight teenagers to diet, the teenagers are at higher risk of lower self-esteem and depression and of being overweight five years later.

Research by Dianne Neumark-Sztainer, a professor at the University of Minnesota, found that when parents talked to their teens about losing weight, teenagers were more likely to diet, use unhealthy weight-control behaviors and binge eat. Those behaviors are less likely to develop when conversations with parents focused on healthy eating behaviors, rather than weight per se.

Harsh comments about weight can send the message that parents are “tying weight to some kind of perception about how the child is valued,” Dr. Puhl said, and that can trigger negative feelings. “The children are internalizing that, and thinking they’re not O.K. as a person. And that is what’s leading to other outcomes, like disordered eating.”

So what’s a parent to do? Do they just stand by while their child gains weight?

Dr. Neumark-Sztainer was besieged by parents asking her this question, and wondering, “How do I prevent them from getting overweight and still feel good about themselves?”

In her book, called “I’m, Like, SO Fat: Helping Your Teen Make Health Choices About Eating and Exercise in a Weight-Obsessed World,” she notes that parents can influence a child’s eating habits without talking about them. “I try to promote the idea of talking less and doing more — doing more to make your home a place where it’s easy to make healthy eating and physical activity choices, and talking less about weight.”

For parents, that means keeping healthy food in the house and not buying soda. It means sitting down to enjoy family dinners together, and also setting an example by being physically active and rallying the family to go for walks or bike rides together. Modeling also means not carping about your own weight. “Those actions speak louder than words,” Dr. Puhl said.

While your children are young, “there doesn’t need to be a conversation at all – it really is just about what’s being done at home,” Dr. Neumark-Sztainer said.

If an older child is overweight, “wait for your child to bring it up, and be there to support them when they do,” she said. “Say, ‘Look, I love you no matter what size you are, but if you would like, I will support you. I suggest we focus not so much on your weight but on your eating patterns and behaviors. What would be helpful for you?’”

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Is Sugar Really Bad for You? It Depends

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Credit iStock

The federal government’s decision to update food labels last month marked a sea change for consumers: For the first time, beginning in 2018, nutrition labels will be required to list a breakdown of both the total sugars and the added sugars in packaged foods. But is sugar really that bad for you? And is the sugar added to foods really more harmful than the sugars found naturally in foods?

We spoke with some top scientists who study sugar and its effects on metabolic health to help answer some common questions about sugar. Here’s what they had to say.

Why are food labels being revised?

The shift came after years of urging by many nutrition experts, who say that excess sugar is a primary cause of obesity and heart disease, the leading killer of Americans. Many in the food industry opposed the emphasis on added sugars, arguing that the focus should be on calories rather than sugar. They say that highlighting added sugar on labels is unscientific, and that the sugar that occurs naturally in foods like fruits and vegetables is essentially no different than the sugar commonly added to packaged foods. But scientists say it is not that simple.

So, is added sugar different from the naturally occurring sugar in food?

It depends. Most sugars are essentially combinations of two molecules, glucose and fructose, in different ratios. The sugar in a fresh apple, for instance, is generally the same as the table sugar that might be added to homemade apple pie. Both are known technically as sucrose, and they are broken down in the intestine into glucose and fructose. Glucose can be metabolized by any cell in the body. But fructose is handled almost exclusively by the liver.

“Once you get to that point, the liver doesn’t know whether it came from fruit or not,” said Kimber Stanhope, a researcher at the University of California, Davis, who studies the effects of sugar on health.

The type of sugar that is often added to processed foods is high-fructose corn syrup, which is the food industry’s favored sweetener for everything from soft drinks to breads, sauces, snacks and salad dressings. Made commercially from cornstarch, high-fructose corn syrup is generally much cheaper than regular sugar. It contains the same components as table sugar – glucose and fructose – but in slightly different proportions.

What about “natural” sweeteners?

Food companies like to market agave nectar, beet sugar, evaporated cane juice and many other “natural” sweeteners as healthier alternatives to high-fructose corn syrup. But whatever their source, they are all very similar. To suggest one is healthier than another is a stretch, experts say. In fact, last month, the F.D.A. urged food companies to stop using the term evaporated cane juice because it is “false or misleading” and “does not reveal that the ingredient’s basic nature and characterizing properties are those of a sugar.”

Is high-fructose corn syrup worse than regular sugar? How is it different?

High-fructose corn syrup and regular sugar are so similar that most experts say their effects on the body are essentially the same.

The main difference is that the variety of high-fructose corn syrup used in soft drinks tends to have more fructose. In one 2014 study, researchers analyzed more than a dozen popular soft drinks and found that many sweetened with high-fructose corn syrup – including Pepsi, Sprite, Mountain Dew, Coca-Cola and Arizona Iced Tea – contained roughly 40 percent glucose and 60 percent fructose. Regular sugar contains equal parts glucose and fructose.

Why doesn’t the F.D.A. require that added sugars be listed in teaspoons rather than grams?

When the new food labels go into effect, the daily recommended limit for added sugars will be 50 grams, or roughly 12 teaspoons, daily. (One teaspoon of sugar is 4.2 grams.) But the new food labels will list the amount of added sugars solely in grams.

Many nutrition advocates have urged the F.D.A. to require that food labels list added sugars in both teaspoons and grams on food labels, arguing that Americans often underestimate the actual amount of sugar in a product when it’s expressed in grams alone.

But the F.D.A. ultimately sided with the food industry, which opposed the teaspoon proposal.

“It would be difficult, if not impossible, for a manufacturer to determine the volume contribution that each ingredient provides toward the added sugars declaration,” the agency said. “For example, a cookie made with white chocolate chips and dried fruit would have added sugars in the form of sugar in the batter as well as in the white chocolate chips and the dried fruit.” The F.D.A. also said that requiring both grams and teaspoons would “cause clutter and make the labels more difficult to read.”

But Michael Jacobson, the president of the Center for Science in the Public Interest, an advocacy group that had petitioned the F.D.A. to require the teaspoon measurement, said the agency was under enormous pressure from the food industry, “which knows that consumers would be far more concerned about a product labeled 10 teaspoons than 42 grams.”

So what’s the issue with added sugars?

It mainly comes down to the way they’re packaged.

Naturally occurring sugar is almost always found in foods that contain fiber, which slows the rate at which the sugar is digested and absorbed. (One exception to that rule is honey, which has no fiber.) Fiber also limits the amount of sugar you can consume in one sitting.

A medium apple contains about 19 grams of sugar and four grams of fiber, or roughly 20 percent of a day’s worth of fiber. Not many people would eat three apples at one time. But plenty of children and adults can drink a 16-ounce bottle of Pepsi, which has 55 grams of added sugar – roughly the amount in three medium apples – and no fiber. Fiber not only limits how much you can eat, but how quickly sugar leaves the intestine and reaches the liver, Dr. Stanhope said.

“You can’t easily eat that much sugar from fruit,” she said. “But nobody has any problem consuming a very high level of sugar from a beverage or from brownies and cookies.”

Why is it a problem to have too much sugar?

Many nutrition experts say that sugar in moderation is fine for most people. But in excess it can lead to metabolic problems beyond its effects on weight gain. The reason, studies suggest, is fructose. Any fructose you eat is sent straight to your liver, which specializes in turning it into droplets of fat called triglycerides.

“When you ingest fructose, almost all of it is metabolized by the liver, and the liver is very good at taking that fructose and converting it to fat,” said Dr. Mark Herman, an assistant professor of medicine at Harvard. Studies show a predictable response when people are asked to drink a sugary beverage: A rapid spike in the amount of triglycerides circulating in their bloodstreams. This also leads to a reduction in HDL cholesterol, the so-called good kind.

Over time, this combination – higher triglycerides and lower HDL – is one major reason sugar promotes heart disease, said Dr. Aseem Malhotra, a cardiologist and adviser to the United Kingdom’s national obesity forum. This sequence of events may even overshadow the effects of LDL cholesterol, the so-called bad kind.

“What many people don’t realize is that it’s triglycerides and HDL that are more predictive of cardiovascular disease than LDL cholesterol,” Dr. Malhotra said. “I’m not saying LDL isn’t important. But if there is a hierarchy, triglycerides and HDL are more important than LDL.”

Dr. Malhotra said that when people reduce their sugar intake, “their overall cholesterol profile improves.”

“I see this in so many of my patients,” he added. “The effects are rapid.”

How much sugar is too much?

One of the largest studies of added sugar consumption, which was led by the Centers for Disease Control and Prevention, found that adults who got more than 15 percent of their daily calories from added sugar had a higher risk of cardiovascular disease. For the average adult, that translates to about 300 calories, or 18 teaspoons of added sugar, daily. That may not sound like a lot. But considering that a single 12-ounce can of Coca-Cola has almost 10 teaspoons of sugar, it can add up quickly

The study found that most adults got more than 10 percent of their daily calories from added sugar, and that for 10 percent of people, more than 25 percent of their calories came from added sugar. The biggest sources for adults were soft drinks, fruit juices, desserts and candy.

While those might seem like obvious junk foods, Dr. Malhotra said, about half of the sugar Americans consume is “hidden” in less obvious places like salad dressings, bread, low-fat yogurt and ketchup. In fact, of the 600,000 food items for sale in America, about 80 percent contain added sugar.

Everyone’s tolerance for sugar is different. Studies show, for example, that people who are already obese may be more susceptible to metabolic harm from sugar than others. But Dr. Malhotra said that he generally advises people to follow the World Health Organization’s guidelines, which recommend that adults and children consume no more than about six teaspoons daily of added sugar.

“Could I tell you the exact limit where sugar starts to definitely impact cardiovascular health?” he said. “That’s difficult. But I think if people stick within the W.H.O. limits, then their risk is reduced.”

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Exercise Tied to Lower Risk for 13 Types of Cancer

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Anyone who still needs motivation to move more may find it in a new study showing that, in addition to its other health benefits, exercise appears to substantially reduce the risk of developing 13 different varieties of cancer. That is far more types than scientists previously thought might be impacted by exercise. The comprehensive study also suggests that the potential cancer-fighting benefits of exercise seem to hold true even if someone is overweight.

The idea that exercise might change someone’s susceptibility to cancer is, of course, not new. Many studies have found that people who are physically active, either through exercise or while on the job, tend to be less likely to develop certain types of cancer than people who are sedentary.

But those studies primarily looked at associations between exercise and a few common malignancies, such as breast cancer in women, and colon and lung cancers in both women and men.

Whether physical activity, and more precisely, regular exercise, would also lower our risk for other cancers has remained an open question.

So for the new study, which was published this week in JAMA Internal Medicine, scientists with the division of cancer epidemiology and genetics at the National Cancer Institute, as well as Harvard Medical School, and a number of other institutions around the world turned to a large trove of epidemiological health studies conducted in the United States or Europe.

In these earlier studies, researchers directly measured volunteers’ body mass and other health markers and also asked about their diets and exercise habits. The researchers then tracked the participants for a decade or more, noting disease diagnoses or, in some instances, deaths.

Such studies help to establish links between lifestyles and disease risk. But the number of people involved must be hefty if the associations are to be persuasive.

To gain sufficient numbers now, the Cancer Institute researchers gathered data from 12 large-scale studies that, pooled together, involved 1.44 million men and women.

The researchers focused on specific information for each of those 1.44 million people about whether they exercised, and how vigorously and how often. They also zeroed in on whether and when, after each study’s start, the participant had been diagnosed with any type of cancer.

Then, using elaborate statistical methods, they computed the role that exercise, and in particular, moderate or vigorous exercise such as brisk walking or jogging, seemed to be playing in people’s risks for cancer.

It turned out to be considerable. For most cancers, people who reported exercising moderately, even if the time that they spent exercising was slight, had significantly less risk of developing 13 different types of cancer than people who were sedentary.

The researchers found a reduced risk of breast, lung and colon cancers, which had been reported in earlier research. But they also found a lower risk of tumors in the liver, esophagus, kidney, stomach, endometrium, blood, bone marrow, head and neck, rectum and bladder.

And the reductions in risk for any of these 13 cancers rose steeply as people exercised more. When the researchers compared the top 10 percent of exercisers, meaning those who spent the most time each week engaging in moderate or vigorous workouts, to the 10 percent who were the least active, the exercisers were as much as 20 percent less likely to develop most of the cancers in the study.

On the other hand, they found an increased risk of two types of malignancies — melanoma and slow-growing prostate tumors — among people who exercised the most. Those findings can most likely be explained, in large part, by certain characteristics of active people, said Steven Moore, an investigator at the National Cancer Institute who led the study.

“People who exercise generally go in for more checkups” than sedentary people, he said, resulting in more screenings for conditions such as so-called indolent prostate cancers. (There was no discernible association, positive or negative, between exercise and aggressive prostate tumors.) “They also often exercise outside,” he continued, “and are more prone to sunburns” than people who rarely work out, potentially contributing to a greater risk for melanoma.

Encouragingly, the associations between exercise and reduced cancer risks held true even when the researchers factored in body mass. People who were overweight or obese but exercised had a much lower risk of developing most cancers than overweight people who did not move much.

Just how physical activity may be undercutting the risk for so many disparate types of cancers is not yet fully understood, Dr. Moore said, although he and his colleagues suspect that changes in exercisers’ hormone levels, degree of inflammation, digestion and overall energy balance most likely contribute.

Bear in mind, though, that this was an observational study, so it cannot directly prove that exercise reduces cancer risks, only that there is an association between more exercise and less disease. It also relied on participants’ memories of exercise, which can be unreliable.

But even with those limitations, the findings sturdily suggest that exercise may help to reduce the risk of many types of cancer, “and it has few side effects and doesn’t cost much,” said Dr. Moore, who runs almost every day.

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Can High-Intensity Exercise Help Me Lose Weight? And Other Questions, Answered

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I recently wrote about a study showing that one minute of intense interval training, tucked into a workout that was, in total, 10 minutes long, produced comparable health and fitness benefits to 45 minutes of more moderate, uninterrupted endurance training.

Readers posted almost 400 comments to the article and flooded the Internet and my inbox with questions and sentiments about extremely short workouts. Given the extent of the response and the astuteness of the questions, I thought I would address some of the issues that arose over and over.

Q. Are high-intensity interval workouts actually better for you than longer, endurance-style workouts — or just shorter?

A. Better is such a subjective word. At the moment, the two types of workouts appear to be largely equivalent to each other in terms of a wide variety of health and fitness benefits.

In the study that I wrote about, “1 Minute of All-Out Exercise May Equal 45 Minutes of Moderate Exertion,” for instance, three months of high-intensity interval training practiced three times per week led to approximately the same improvements in aerobic endurance, insulin resistance and muscular health as far longer sessions of moderate pedaling on a stationary bicycle.

One type of workout was not more beneficial than the other, in other words, but one required much, much less time.

Other studies have generally produced similar results, although, to be honest, the science related to interval training for health purposes and not simply for athletic performance remains scant. An interesting new review of past research to be published in June did conclude that, for overweight and obese children, short sessions of intense intervals may lead to greater improvements in endurance and blood pressure than longer bouts of moderate exercise, although the authors did not discuss how best to get children to complete frequent interval sessions.

The upshot of the available science is that if you currently have the time and inclination to complete long-ish, moderate workouts — if you enjoy running, cycling, swimming, walking or rowing for 30 minutes or more, for instance — by all means, continue.

If, on the other hand, you frequently skip workouts because you feel that you do not have enough time to exercise, then very brief, high-intensity intervals may be ideal for you. They can robustly improve health and fitness without overcrowding schedules.

Q.

What about combining brief high-intensity workouts with longer, endurance workouts?

A.

Alternating high-intensity workouts with endurance-style workouts may yield the greatest health and fitness gains of all.

In a 2014 study, a group of sedentary adults began either a standard endurance-training program, in which they pedaled a bicycle moderately for 30 minutes five times a week, or swapped one of those bike rides for an interval session. All of the participants wound up significantly more aerobically fit after 12 weeks.

But the men and women who had completed one interval session per week had developed slightly more overall endurance than the other volunteers. As a result, they had lowered their risk for premature death by about an additional 18 percent, the study’s authors conclude.

Q.

Do I have to use a stationary bicycle for interval training?

A.

Most recent studies of high-intensity intervals have involved computerized stationary bicycles because scientists can easily monitor the riders’ pace and intensity. But there is nothing magical about the equipment. The key to high-intensity interval training is the intensity, which most of us can gauge either with a heart rate monitor or our own honest judgment.

For moderate exercise, your heart rate typically should be between 70 and 85 percent of your maximum. (I recently wrote about how to determine your individual maximum heart rate.) This intensity would feel like about an 8 on an arduousness scale of 1 to 10.

During an intense interval, however, your heart rate should rise to 90 percent of your maximum heart rate, or above. Think of this as feeling like about a 9.5 on the 10-point scale. You maintain that intensity for only 10 or 20 seconds at a time, however, followed by several minutes of very easy exercise before repeating the intense work.

Almost any type of exercise can be used for interval training, including running up the stairs in your office’s stairwell during your lunch hour, said Martin Gibala, a professor of kinesiology at McMaster University in Hamilton, Ontario, and an expert on intervals. (His book about the science and practical implications of high-intensity interval training will be published in early 2017.)

Q.

Will high-intensity intervals help me to lose weight?

A.

Few studies have yet looked at the long-term effects on body weight of exercising exclusively with high-intensity intervals, although some experiments do hint that high-intensity interval training can reduce body fat, at least in the short term.

In a 2015 study, for example, overweight, out-of-shape men who began either to jog or otherwise exercise moderately for an hour five days per week for six weeks or to complete intensive interval training for a few minutes per week all dropped body fat and about the same percentages of fat, despite very different amounts of exercise. Likewise, a group of women recovering from breast cancer who were assigned either to moderate exercise or brief interval training for three weeks lost comparable amounts of body fat during the study.

But these were small-scale, brief experiments. Whether interval training helps or hinders long-term weight control is still unknown.

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To Keep Obesity at Bay, Exercise May Trump Diet

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Young rats prone to obesity are much less likely to fulfill that unhappy destiny if they run during adolescence than if they do not, according to a provocative new animal study of exercise and weight. They also were metabolically healthier, and had different gut microbes, than rats that keep the weight off by cutting back on food, the study found. The experiment was done in rodents, not people, but it does raise interesting questions about just what role exercise may play in keeping obesity at bay.

For some time, many scientists, dieting gurus and I have been pointing out that exercise by itself tends to be ineffective for weight loss. Study after study has found that if overweight people start working out but do not also reduce their caloric intake, they shed little if any poundage and may gain weight.

The problem, most scientists agree, is that exercise increases appetite, especially in people who are overweight, and also can cause compensatory inactivity, meaning that people move less over all on days when they exercise. Consequently, they wind up burning fewer daily calories, while also eating more. You do the math.

But those discouraging studies involved weight loss. There has been much less examination of whether exercise might help to prevent weight gain in the first place and, if it does, how it compares to calorie restriction for that purpose.

So for the new study, which was published last week in Medicine & Science in Sports & Exercise, researchers at the University of Missouri in Columbia and other schools first gathered rats from a strain that has an inborn tendency to become obese, starting in adolescence. (Adolescence is also when many young people begin to add weight.)

These rats were young enough, though, that they were not yet overweight.

After weighing them, the researchers divided the animals into three groups.

One group was allowed to eat as much kibble as they wished and to remain sedentary in their cages. These were the controls.

Another group, the exercise group, also was able to eat at will, but these animals were provided with running wheels in their cages. Rats like to run, and the animals willingly hopped on the wheels, exercising every day.

The final group, the dieting group, was put on a calorie-restricted meal plan. Their daily kibble helpings were about 20 percent smaller than the amount that the runners ate, a portion size designed to keep them at about the same weight as the runners, so that extreme differences in body size would not affect the final results.

After 11 weeks, all of the animals were moved to specialized cages that could measure their metabolisms and how much they moved around. They then returned to their assigned cages for several more weeks, by which time they were effectively middle-aged.

At that point, the control animals were obese, their physiques larded with fat.

The runners and the lower-calorie groups, however, although they also had gained ounces, had put on far less weight than the controls. None were obese.

Both exercise and portion control, in other words, had effectively protected the animals against their fated fatness.

But beneath the skin, the runners and the dieters looked very unalike. By almost all measures, the runners were metabolically healthier, with better insulin sensitivity and lower levels of bad cholesterol than the dieters. They also burned more fat each day for fuel, according to their metabolic readings, and had more cellular markers related to metabolic activity within their brown fat than the dieting group. Brown fat, unlike the white variety, can be quite metabolically active, helping the body to burn additional calories.

Interestingly, the runners also had developed different gut microbes than the dieters, even though they ate the same food. The runners had greater percentages of some bacteria and smaller populations of others than the dieters or the control group; these particular proportions of gut bugs have been associated in a few previous studies with long-term leanness in both animals and people.

Perhaps most striking, “the runners showed no signs of compensatory eating or compensatory inactivity,” said Victoria Vieira-Potter, an assistant professor of nutrition and exercise physiology at the University of Missouri who oversaw the study. They didn’t scarf down more food than the control group, despite running several miles every day and, according to the specialized cages, actually moved around more when not exercising than either of the other groups of rats.

In essence, the runners, while weighing the same as the dieters at the end of the study, seemed better set up to avoid weight gain in the future.

Of course, these were rats, which do not share our human biology or our tangled psychological relationships with food and body fat.

This study also involved young, normal-weight rodents and cannot tell us whether exercise or dieting alone or in combination would aid or hinder weight loss in people (or animals) who already are overweight, Dr. Vieira-Potter said. Metabolisms change once a body contains large amounts of fat, and it becomes increasingly difficult to permanently drop those extra pounds.

So better to avoid weight gain in the first place, if possible. And in that context, she said, “restricting calories can be effective,” but exercise is likely to be more potent in the long term and, of course, as common sense would tell us, doing both—watching what you eat and exercising—is best of all.

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Visiting to Lose Weight, Then Calling It Home

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After a trip to Fitness Ridge, Jennifer Morton ended up staying there.

After a trip to Fitness Ridge, Jennifer Morton ended up staying there.Credit Victoria Tarter

There was no reason for Jennifer Morton to move to Utah, except one: It was the place she lost 40 pounds.

In 2009, Ms. Morton was working 90-hour weeks as the director of learning at a large company outside Louisville, Ky. She traveled 80 percent of the time, and her weight shot up. Panicked and exhausted, she quit her job and checked into Fitness Ridge (now called Movara Fitness Resort), a weight-loss and fitness retreat in southern Utah.

She ended up staying a month.

“All of a sudden I was in a place where everybody was like me,” said Ms. Morton, 40. “It felt like home.”

Five weeks later, it really was: She packed up her belongings and settled into a house less than a mile from the resort in the town of St. George. Not long after, she began teaching classes at Movara on emotional eating and food addiction, guiding clients through their own body battles.

“It just made sense to do this,” Ms. Morton said. The low cost of living was appealing, as was the natural beauty. But most importantly, she could continue the healthy lifestyle she had embraced.

“At the resort, the way you feel about who you are is so important to protect that you’re willing to stay in that environment to make sure it sticks,” said Ms. Morton, who began doing triathlons after her stay. “If you find your best self somewhere, you definitely don’t want to leave it.”

People like Ms. Morton are adopting a model familiar to those fighting substance abuse, who are often encouraged to change their environments and relationships post-rehab in order to “stay clean.” (Minnesota, for example, is half-jokingly referred to as “Minnesober” because of the large number of rehab centers there and the many people in various stages of recovery, who often remain in the state after treatment.)

“Addiction is a lifelong problem that people have to deal with, and it’s the same with weight,” said Dr. William Yancy, director of the Duke Diet and Fitness Center in Durham, N.C. “Even if they reach their goal, it’s something they need help and support with.”

“It speaks to the power of the proverbial ‘toxic food environment,’” said David Sarwer, director of the Center for Obesity Research and Education at Temple University’s College of Public Health. “When we’re in our normal day-to-day routines, and those routines have become second nature to us, there are countless negative influences on our eating habits and sedentary behavior that contributes to weight gain.”

Relocating, he said, offers an opportunity to create new habits. “In these cases, people have the opportunity to make a significant commitment to health and well-being to live in a geographical location that promotes health,” he said.

From 2007 to 2012, Marjorie S. Fine went twice a year to the Duke diet and fitness program. She would lose about 30 pounds during her two-month stay, and regain half when she returned home to Miami. “I would chip away at the weight, but never really be anywhere near 99 percent successful,” said Ms. Fine, 69.

Late in 2015, she and her husband moved full-time to Durham (once called the “diet capital of the world” because of the number of weight-loss facilities there). She exercises and eats lunch at Structure House, a residential program in town, six days a week, and attends individual therapy and weekly Overeaters Anonymous meetings there.

“As with any other addiction, you have to work on it on a daily basis,” said Ms. Fine, who has now lost 65 pounds and hopes to lose another 40.

“It’s very important to have that shared experience and problem solve together,” said Catherine J. Metzgar of the University of Illinois at Urbana-Champaign, the lead author of a study that found social support and being accountable to others helped some women lose and maintain weight loss. “Having your family and others in your social circle buy into what you are doing is also important.”

Cindy MacKenzie, 62, a former teacher and self-described yo-yo dieter, retired with her husband in 2015 to southern Utah. The couple purchased a home about a five-minute drive down the road from Movara, where Ms. MacKenzie used to go for annual weight-loss visits.

“We have definitely bought into the program,” said Ms. MacKenzie, who still regularly attends the resort. Back in Silicon Valley, where they used to live, “we would go out to eat all the time, we would drink. Here, there are no threats, no temptations.”

“If you’re living in a community where every single one of your friends and family members is devoted to overeating and an unhealthy lifestyle or to misusing various drugs and alcohol, it’s really hard to change in that environment,” said Maia Szalavitz, a former heroin and cocaine addict and author of the book “Unbroken Brain: A Revolutionary New Way of Understanding Addiction.”

On the other hand, surrounding yourself with too many people with similar issues can be risky. “A lot of people get into a very closed world that’s kind of limited,” she said. “Sometimes you make each other better, and sometimes worse.”

Of course, most of us cannot afford to uproot our families, lives and jobs in the name of healthy living. (Structure House’s base price for new participants, for example, is $10,500 for a four-week stay.) And even if we could, we bring our struggles with us. (In bumper sticker terms: “Wherever you go, there you are.” )

Jean Anspaugh, 62, lost 100 pounds at the Rice House program in Durham, where she stayed for seven years, renting an apartment nearby and taking odd jobs to pay the costs. She figured she would “stay thin forever.” But she didn’t. Work, bills and relationships took their toll, and she got “mainstreamed back into the dominant culture, which eats all the time.”

“Nobody realizes how hard it is to lose weight and keep it off,” said Ms. Anspaugh, a folklorist in Fairfax, Va., and author of “Fat Like Us.” “It’s a full-time job.” She has regained some of the weight but still feels that Durham, “the place where the magic happened,” is home. “I miss the mind-set,” she said. “I miss my tribe.”

Ms. Morton, too, acknowledged that moving to Utah wasn’t a panacea. “You still have to do the same things: build your community, get involved, find the people you like,” she said. And she now is wrestling with “emotional management — meaning, working through the parts of myself that will keep me successful over the long run.”

Still, she has no plans to leave.

“Weight and fitness is definitely on the forefront of my mind, so I think it keeps me accountable because I have to face it every day,” she said. “Also, it helped me realize — we’re all the exact same. We are all dealing with the same set of four or five problems; they just manifest differently in each one of us. It has helped me on my weight management program, and also on my journey to be a good human.”

Intermittent Fasting Diets Are Gaining Acceptance

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Credit Gary Taxali

Mark Mattson, a neuroscientist at the National Institute on Aging in Maryland, has not had breakfast in 35 years. Most days he practices a form of fasting — skipping lunch, taking a midafternoon run, and then eating all of his daily calories (about 2,000) in a six-hour window starting in the afternoon.

“Once you get used to it, it’s not a big deal,” said Dr. Mattson, chief of the institute’s laboratory of neurosciences. “I’m not hungry at all in the morning, and this is other people’s experience as well. It’s just a matter of getting adapted to it.”

In a culture in which it’s customary to eat three large meals a day while snacking from morning to midnight, the idea of regularly skipping meals may sound extreme. But in recent years intermittent fasting has been gaining popular attention and scientific endorsement.

It has been promoted in best-selling books and endorsed by celebrities like the actors Hugh Jackman and Benedict Cumberbatch. The late-night talk show host Jimmy Kimmel claims that for the past two years he has followed an intermittent fasting program known as the 5:2 diet, which entails normal eating for five days and fasting for two — a practice Mr. Kimmel credits for his significant weight loss.

Photo

Credit Gary Taxali

Fasting to improve health dates back thousands of years, with Hippocrates and Plato among its earliest proponents. Dr. Mattson argues that humans are well suited for it: For much of human history, sporadic access to food was likely the norm, especially for hunter-gatherers. As a result, we’ve evolved with livers and muscles that store quickly accessible carbohydrates in the form of glycogen, and our fat tissue holds long-lasting energy reserves that can sustain the body for weeks when food is not available.

“From an evolutionary perspective, it’s pretty clear that our ancestors did not eat three meals a day plus snacks,” Dr. Mattson said.

Across the world, millions of people fast periodically for religious and spiritual reasons. But some are now looking at the practice as a source of health and longevity.

Valter Longo, the director of the Longevity Institute at the University of Southern California, initially studied fasting in mice that showed that two to five days of fasting each month reduced biomarkers for diabetes, cancer and heart disease. The research has since been expanded to people, and scientists saw a similar reduction in disease risk factors.

Dr. Longo said the health benefits of fasting might result from the fact that fasting lowers insulin and another hormone called insulinlike growth factor, or IGF-1, which is linked to cancer and diabetes. Lowering these hormones may slow cell growth and development, which in turn helps slow the aging process and reduces risk factors for disease.

“When you have low insulin and low IGF-1, the body goes into a state of maintenance, a state of standby,” Dr. Longo said. “There is not a lot of push for cells to grow, and in general the cells enter a protected mode.”

Critics say that health benefits or not, various forms of intermittent fasting are too impractical for most people.

The 5:2 diet, for example, advocates eating without restrictions for five days and then consuming just 500 calories — roughly the equivalent of a light meal — on each of the other two days of the week. Another regimen, called alternate-day fasting, involves eating no more than 500 calories every other day.

A third regimen, which Dr. Mattson follows, is known as time-restricted feeding. The idea is to consume all of the day’s calories in a narrow window, typically six to eight hours, and fasting for the remaining 16 to 18 hours in a day. Studies of time-restricted feeding practices in both animals and humans have suggested that the practice may lower cancer risk and help people maintain their weight.

The scientific community remains divided about the value of intermittent fasting. Critics say that the science is not yet strong enough to justify widespread recommendations for fasting as a way to lose weight or boost health, and that most of the evidence supporting it comes from animal research. Advocates say the body of research on intermittent fasting is growing rapidly and indicates that the health benefits are striking.

The 5:2 diet, in particular, is backed by “promising” studies that show that it lowers weight and improves blood sugar, inflammation and other aspects of metabolic health, said Joy Dubost, a registered dietitian and a spokeswoman for the Academy of Nutrition and Dietetics, the country’s largest organization of dietitians. She noted that fasting isn’t appropriate for pregnant women, people with diabetes and people on medications.

“Most people who do this understand that it’s not about binge eating,” Dr. Dubost said. “But they like that it gives them the freedom not to worry about calories, carbs and other restrictions on days when they’re not fasting.”

Krista Varady, an associate professor of nutrition at the University of Illinois at Chicago, has studied the effects of alternate-day fasting on hundreds of obese adults. In trials lasting eight to 10 weeks, she has found that people lose on average about 13 pounds and experience marked reductions in LDL cholesterol, blood pressure, triglycerides and insulin, the fat-storage hormone.

Dr. Varady found in her research that intermittent fasting was easiest when people ate a moderately high-fat diet and were allowed to consume up to 500 calories on their fasting days. In her studies, 10 percent to 20 percent of people usually find the diet too difficult and quickly stop. Those who stick with it typically adjust after a rocky first few weeks.

“We’ve run close to 700 people through various trials,” Dr. Varady said. “We thought people would overeat on their feast days to compensate. But people for some reason, regardless of their body weight, can only eat about 10 or 15 percent more than usual. They don’t really overeat, and I think that’s why this works.”

In 2011, Dr. Mattson and his colleagues reported a study of the 5:2 program that followed 107 overweight and obese women. Half of the subjects were assigned to eat no more than 500 calories each on two consecutive days each week. A control group was assigned to follow a low-calorie diet.

After six months, both groups had lost weight. But the intermittent fasting group lost slightly more — about 14 pounds on average — and had greater reductions in belly fat. They also retained more muscle and had greater improvements in blood sugar regulation.

Dr. Mattson’s interest in intermittent fasting grew out of work on animals that showed that alternate-day fasting protected mice from strokes, Alzheimer’s and Parkinson’s disease, and consistently extended their life spans by 30 percent. Dr. Mattson and his colleagues found that alternate-day fasting increased the production of proteins that protect brain cells, enhancing their ability to repair damaged DNA. Fasting, he said, acts as a mild stress that makes cells throughout the body stronger, shoring up their ability to adapt to later insults.

In this way, intermittent fasting is like exercise, which causes immediate stress and inflammation, but protects against chronic disease in the long run. Eating fruits and vegetables may have a similar effect. While very large doses of antioxidants can cause cancer in humans, moderate amounts of exposure can make cells more resilient, Dr. Mattson said.

“There is overlap between the way cells respond to exercise, to fasting, and even to exposure to some of the chemicals in fruits and vegetables,” he added.

Dr. Mattson is now starting a rigorous clinical trial of people 55 to 70 years old who are prediabetic and at high risk for developing Alzheimer’s disease. He plans to study whether intermittent fasting may slow cognitive decline.

Dr. David Ludwig, a professor of nutrition at the Harvard T. H. Chan School of Public Health, said one benefit of fasting is that it forces the body to shift from using glucose for fuel to using fat. During this process, the fat is converted to compounds known as ketones, a “clean” energy source that burns more efficiently than glucose, like high-octane gasoline, Dr. Ludwig said.

The same process, known as ketosis, occurs when people go on extremely low-carb, high-fat diets. Dr. Ludwig said ketones seem to have unique effects on the brain. High-fat diets, for example, have been used for years to treat people who suffer from epileptic seizures.

“There are extensive reports of children who had debilitating seizures who were cured on ketogenic diets,” Dr. Ludwig said. “If it benefits the brain to prevent seizures, then maybe it benefits the brain in other ways.”

Dr. Ludwig noted that the long-term effectiveness of fasting had not been well studied. He cautioned that for many people, fasting is simply too difficult and may slow metabolism. A potentially more practical approach is to limit sugar and other processed carbohydrates, replacing them with natural fats, protein and unrefined carbohydrates, he said.

“It takes a very disciplined person to skip a couple meals every day,” he added.

But Dr. Mattson, who has been skipping meals for decades, said the adjustment to skipping breakfast and lunch was a lot like the change that occurs when a couch potato starts exercising.

“If you’ve been sedentary for years and then you go out and try to run five miles, you’re not going to feel very good until you get in shape,” he said. “ It’s not going to be a smooth transition right away. It takes two weeks to a month to adapt.”

Have You Tried a Fasting Diet? Tell Us About It.

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