Tagged Carbohydrates

No Health Benefit to Replacing Fat With Carbs

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Low-fat diets that are high in carbohydrates are unlikely to improve your health, a new study shows.

Researchers came to the conclusion after studying the eating habits and health behaviors of 126,233 men and women who completed health questionnaires every two to four years for up to 32 years. Then they calculated the effect of replacing just 5 percent of saturated fat calories with another type of fat or carbohydrates.

The study, in JAMA Internal Medicine, found that replacing 5 percent of daily calories from saturated fats (mainly animal fat) with foods high in monounsaturated fat, such as olive oil and avocados, was associated with a 27 percent reduction in total mortality and reduced death from cardiovascular disease, cancer and neurodegenerative disease.

A similar switch from saturated fat to polyunsaturated fats, such as the omega-3 and omega-6 fatty acids in fish and walnuts, was associated with a 13 percent reduction in total mortality and a 29 percent reduction in death from neurodegenerative diseases.

But replacing saturated fats with carbohydrates, such as sugars and refined grains, did not confer any health benefits.

“Not all fats are created equal,” said the senior author, Dr. Frank B. Hu, a professor of nutrition at the Harvard T.H. Chan School of Public Health. “We should eat more good ones from fish and avocados, instead of animal fats. And second, the low-fat, high-carbohydrate diet is not beneficial for improving health and longevity.”

For Serious Training, Hold the Carbs at Dinnertime

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Triathletes plunged into the Hudson River for the 12th annual N.Y.C. Triathlon held in 2012.

Triathletes plunged into the Hudson River for the 12th annual N.Y.C. Triathlon held in 2012.Credit Christopher Gregory for The New York Times

Strategically skipping bread, pasta and other carbohydrates at dinner might improve subsequent athletic performance, provided those low-carb meals are combined with the right types of workouts, according to a new sports nutrition study. Its findings undercut some entrenched ideas about how athletes should eat in preparation for spring marathons and other endurance races.

As those of us who are athletes or spend time around them know, diets are a topic of consuming interest for the group, since an athlete’s diet affects how well he or she can train, recover, progress, chisel a physique and compete.

But the ideal sports diet remains elusive. Many dietitians and coaches advocate for heaps of carbohydrates at the training table. Carbohydrates, which break down during digestion into sugar, are the body’s first choice as fuel during exercise. But the body’s reservoir of stored carbohydrates is small, and even if athletes supplement their supply during exercise with sugary drinks or food, prolonged or intense exertion generally incinerates much of the body’s available carbohydrates.

Consequently, some experts suggest that athletic success may depend in part on making the body better able to use fat as a fuel. Even the leanest athlete’s body is girded with the stuff, theoretically providing enough energy for even the longest, hardest workouts. Low-carbohydrate diets will force the body to turn to fat. But working muscles must become used to burning fat, a process that can make exercising on a low-carb diet difficult in the short term. Indeed, athletes on extremely low-carbohydrate diets tend to struggle to finish hard workouts.

So researchers at the French National Institute of Sport, Expertise and Performance in Paris and other institutions began to wonder about the possibilities of modified forms of low-carb diets, and specifically about what they and other scientists call “sleeping low.”

With a “sleep-low” sports diet, an athlete skips carbohydrates at dinner. In the morning, his or her body should have low reserves of the macronutrient, and any ensuing workouts would force the body to turn to fat, its most abundant fuel. In past studies of the technique, however, it has produced mixed results in terms of whether it improves competitive performance.

The authors of the new study, which was published in January in Medicine & Science in Sports & Exercise, suspected that the sleep-low diet needed to be integrated into a broader training plan in order to show desirable results.

To test that possibility, they recruited 21 experienced, competitive triathletes who bravely agreed to have their diets manipulated. The scientists ran their volunteers through a simulated triathlon and other tests of their current fitness and pace.

Half of the athletes were then randomly assigned to eat a standard sports diet, with large helpings of carbohydrates at every meal and after workouts.

The others were put on a sleep-low regimen. With this program, the athletes consumed the same amount of carbohydrates over the course of the day as the other group, but in a different sequence. Virtually all of their carbohydrates were consumed at breakfast and lunch, with none at dinner.

At the same time, all of the athletes also began a new training program. In the afternoon, both groups completed a draining, intense interval-training session, designed to increase fitness and deplete the body’s carbohydrate stores. The members of the control group then replenished their carbohydrates at dinner; the sleep-low group did not.

Next morning, before breakfast, the volunteers pedaled for an hour at a moderate pace on stationary bicycles. By this time, the sleep-low group was running on carbohydrate fumes and body fat.

Afterward, all of the athletes sat down to large, carb-rich breakfasts and lunches, meaning that both groups were flush with carbohydrates for the afternoon interval training.

This program continued for four days per week for three weeks. (On the remaining days, the athletes ran, cycled or swam at an easy pace and ate as they chose.)

After three weeks, the athletes in the sleep-low group were grumbling about evening hunger.

But when the researchers now repeated the simulated triathlon, those athletes in the sleep-low group showed notable improvement. Their times on the 10-kilometer running leg at the end of the race were faster by about 75 seconds, or 3 percent, than at the start of the study. The control group had not improved.

The sleep-low volunteers also had lost body fat, while the other athletes had not.

These findings suggest, said Laurie-Anne Marquet, a graduate student at the French National Institute of Sport who led the study, that exercising strenuously in the afternoon, depriving yourself of carbohydrates afterward, training gently the next morning and then swallowing a mound of pancakes might be a useful way to improve endurance and performance. The regimen seemed to have increased the athletes’ ability to access fat as muscle fuel, she said, allowing them to exercise harder during the workouts than the control group and gain additional fitness and speed.

Such a rigorous routine is not for everyone, of course. Those of us not training for a marathon, triathlon or similar event probably would not enjoy or benefit from sleeping low. Even serious athletes should thread the approach into their training cautiously, Ms. Marquet said, beginning a few weeks before a race and easing off in the days just before the event, when they should down carbohydrates at will.

Encouragingly for those tempted by the diet, though, “most of the athletes” in the study, Ms. Marquet said, “have now integrated this strategy into their training.”

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Making a Case for Eating Fat

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Credit

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Credit Mark Hyman

For years Dr. Mark Hyman was a vegetarian who kept his intake of dietary fat to a minimum. Whole-wheat bread, grains, beans, pasta and fruits and vegetables made up the bulk of his diet, just as the federal government’s dietary guidelines had long recommended. But as he got older, Dr. Hyman noticed something that bothered him: Despite plenty of exercise and a seemingly healthy diet, he was gaining weight and getting flabby.

At first he wrote it off as a normal part of aging. But then he made a shift in his diet, deciding to eat more fat, not less – and the changes he saw surprised him.

He lost weight, his love handles disappeared, and he had more energy. He encouraged his patients to consume more fat as well, and many of them lost weight and improved their cholesterol. Some even reversed their Type 2 diabetes.

Today, as the director of the Cleveland Clinic’s Center for Functional Medicine, Dr. Hyman has become an outspoken advocate about the health benefits of eating fat. He promotes it on talk shows, educates other doctors, and has even managed to wean his close friend Bill Clinton off of his previously prescribed low-fat vegan diet.

Now in a new book called “Eat Fat, Get Thin,” Dr. Hyman takes a deep dive into the science behind dietary fat, making sense of decades of confusing health recommendations and building a case for why even saturated fats, which have long been vilified, belong in a healthy diet. Dr. Hyman argues that Americans have been misled about the benefits of fat because of a disconnect between nutrition science and food policy. In the book he challenges the nutrition orthodoxy while also exploring the food industry’s outsize influence on official health recommendations.

Recently, we sat down with Dr. Hyman to discuss his thoughts on the gap between nutrition science and health recommendations, the reason you should always plan your meals, and why he never leaves home without a stash of “emergency foods” in his backpack. Here are edited excerpts from our conversation:

Q.

Why did you write “Eat Fat, Get Thin”?

A.

I wrote it because we’ve been suffering from 40 years of bad advice about fat that’s led to the biggest obesity and diabetes epidemic in history. The myth that fat makes you fat and causes heart disease has led to a total breakdown in our nutritional framework. I felt it was important to tell the story of how fat makes you thin and how it prevents heart disease and can reverse diabetes. I think people are still very confused about fat.

Q.

In the book you argue that nutrition recommendations are often contradictory. How so?

A.

This year, for example, the U.S. Dietary Guidelines for the first time removed their longstanding restrictions on dietary fat. But they still have recommendations to eat low-fat foods. They say total fat is not an issue, but you should drink low-fat milk and eat low-fat dairy and other low-fat foods. It’s a schizophrenic recommendation from the government, and it’s the same with other professional organizations such as the American College of Cardiology and the American Heart Association. There’s a mismatch between the science and the government and professional recommendations.

Q.

What’s driving this disconnect?

A.

I think the government based its recommendations on some very flawed science, which took hold. It became policy that was turned into the dietary guidelines and the food pyramid that told us to eat six to 11 servings of bread, rice, cereal and pasta a day and to eat fats and oils sparingly. It’s very hard to overturn dogma like that. It’s embedded in our culture now. It’s embedded in food products. The food industry jumped on the low-fat bandwagon, and the professional associations kept driving the message. Unfortunately the science takes decades to catch up into policy and into practice. And I’m trying to close that gap by bringing awareness to the latest science on how fats and carbs work in your body.

Q.

You reviewed hundreds of studies while writing this book. What is your conclusion on saturated fat?

A.

It’s a huge area of controversy. But large reviews of randomized trials, observational research and blood-level data have all found no link between saturated fat or total fat and heart disease. Yet there are still recommendations to limit saturated fat because it raises total cholesterol and LDL cholesterol. But it also raises HDL, and it increases cholesterol particle size, so you actually get a net benefit.

Q.

What do you say to scientists who argue that saturated fat does in fact cause heart disease?

A.

I think the challenge with the research is that a lot of the data combines saturated fat in the context of a high-carbohydrate diet. The real danger is sweet fat. If you eat fat with sweets – so sugar and fat, or refined carbohydrates and fat – then insulin will rise and it’ll make you fat. But if you eliminate the refined carbs and sugar, that doesn’t happen. I think saturated fats can be bad in the context of a high-carbohydrate diet. But in the absence of that, they’re not.

Q.

What foods do you eat and recommend to your patients?

A.

What I eat is a cross between paleo and vegan diets. It combines elements of the two, so I call it a “pegan” diet. It’s low in sugars and refined carbs, and it’s very high in plant foods. About 70 to 80 percent of your diet should be plant foods. It should also include good-quality fats like nuts and seeds, olive oil, avocado, coconut oil and fatty fish. It should basically include whole, fresh food that’s unprocessed and high in fiber and phytonutrients. I always say that vegetables should make up 50 to 75 percent of your plate.

Q.

In a world where fast food is everywhere, wouldn’t that be fairly difficult for most people?

A.

It’s actually very easy to eat well if you just know what to do. The reason most people don’t succeed is they don’t plan their food. They plan their vacations, they plan their kitchen redesign, but they don’t plan out what they’re eating, and that’s a recipe for failure. I always think through how and where I’m going to get my food every day of every week. I also carry with me a set of emergency food so that I’m never in a food emergency.

Q.

What are the “emergency foods” that you carry?

A.

I have to protect myself from myself because I’ll eat whatever if I’m hungry in an airport. So I always carry packets of almond butter, cashew butter, an Evolution bar, a Bulletproof bar, a Tanka bar and a KIND bar. I basically have fat and protein as my snacks, and I have enough food in my bag to last an entire day so I don’t make bad choices.

Q.

We talked a lot about fat. But what is one overarching message you would most like people to understand?

A.

I think we have to get rid of the prevailing dogma that all calories are the same, and that we just need to exercise more and eat less, which is what the food industry and the government promote. The truth is that you can’t exercise your way out of a bad diet. Metabolism is not a math problem. It’s a hormonal problem. Food is not just energy. It’s information. It’s instructions that turn on or off different switches in your body that regulate hunger and metabolism. Obesity is not about how much you eat. It’s about what you eat. If you just focus on quality, not calories, then the quantity takes care of itself.

Ask Well: The Sugar in Fruit

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Credit Andrew Scrivani for The New York Times

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Sophie Egan is the director of programs and culinary nutrition for strategic initiatives at the Culinary Institute of America. She is the author of the forthcoming book “Devoured: From Chicken Wings to Kale Smoothies — How What We Eat Defines Who We Are” (William Morrow, May 2016).

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