Intermittent Fasting Does Not Lead to More Weight Loss

Participants in a new randomized clinical trial lost about the same amount of weight and had similar cardiometabolic benefits whether they practiced intermittent fasting (time-restricted eating) or ate three meals per day. One group of the overweight and obese participants were told to eat three meals a day (plus snacks if desired). Another group could eat whatever they wanted between the hours of noon and 8 PM, with no caloric intake for the rest of the 24-hour day (eight hours to eat, 16 hours of fasting). The study did not include calorie restriction for either group.

After 12 weeks, there was no significant difference in weight change between groups. And, the group randomized to intermittent fasting actually experienced a significant loss of lean muscle mass: an unexpected and potentially harmful result. The authors had hypothesized that the fasting schedule would lead to lower calorie intakes and, hence, weight loss, but the results did not support that hypothesis. Some other studies have found intermittent fasting to be as effective for weight loss as other weight-loss diets; however, these studies have been relatively short term. For now, no strong evidence supports intermittent fasting regimens compared to three healthy meals per day as a more effective way to lose weight. (See page 6 for more information.)