Alternate-day fasting has gained some popularity as a weight-loss technique, but a rigorous trial has found that it works no better than ordinary calorie restriction.
Researchers randomized 100 overweight and obese people to one of three groups: alternate-day fasting; a diet restricted to 75 percent of regular daily energy intake; and a control group that followed their usual eating plan. The researchers tracked calorie intake, and all participants were generally healthy at the start of the study.
At six months, both the fasting and the calorie restricted groups had lost 6.8 percent of their weight. By one year, the fasting group was down 6 percent, and the calorie restriction group 5.3 percent. In other words, there was no statistically significant difference between the two diets. The alternate-day fasting group had the highest dropout rate: 38 percent dropped out of the study, compared with 29 percent for the calorie restriction group and 26 percent for the controls.
There was no significant difference between the groups in the reduction of cardiovascular risk factors like blood pressure, cholesterol or triglycerides. The study is in JAMA Internal Medicine.
The senior author, Krista A. Varady, an associate professor of nutrition at the University of Illinois, Chicago, said that while fasting is not for everyone, it could be worth a try.
In any case, she added, “There’s nothing magical here. We’re tricking people into eating less food, in different ways.”