A new study suggests that fasting every other day is no better than restricting calorie intake every day for people trying to lose weight.
The study of 100 people over the course of one year suggests that weight loss on either type of diet was about the same, about 6 percent of body weight on an alternate-day fasting diet and 5.3 percent for those on the daily restricted-calorie diet.
The results of this randomized clinical trial demonstrated that alternate-day fasting did not produce superior adherence, weight loss, weight maintenance, or improvement in risk indicators for cardiovascular disease compared with daily calorie restriction.
But the researchers also found that people do not change their eating habits easily. About a third of the study participants who were asked to fast didn’t follow the study requirements and ended up dropping out.
People on the conventional diet were able to stick to their goals better than the alternate-day fasting group, the researchers found.
“We thought the alternate-day fasting group would do better. It allows people to have a break from dieting every other day, so we thought their adherence would be better,” explained lead author Krista Varady. “But it turns out people in both diets lost the same amount of weight.”
“That doesn’t mean that alternate-day fasting doesn’t work.” However, “people who stuck to the [alternate-day fasting] diet lost 20 to 50 pounds in a year,” Varady added. “It does work for some people.”
Some people really love this lifestyle and have been on the fasting diet for years, but it’s not for everyone, Varady said. “People should find what works for them,” she added.
The study has several limitations. First, the duration of the maintenance phase was short. Second, the control group was imperfect, in that they received no food, no counseling, and less attention from study personnel, relative to the intervention groups, which may have confounded the findings.
The study was published in the journal JAMA Internal Medicine.