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Time-Restricted Eating Shows No Weight Loss Benefit in RCT

The popular new weight-loss approach of eating within a restricted window of time during the day, allowing for an extended period of fasting — also known as intermittent fasting — does not result in greater weight loss compared with nonrestricted meal timing, results from a randomized clinical trial show. Although some prior research has shown benefits with time-restricted eating, these studies have been small and lacked control groups.

The study, published online in JAMA Internal Medicine, involved 116 participants who were randomized to a 12-week regimen of either three structured meals per day or time-restricted eating, with instructions to eat only between 12:00 pm and 8:00 pm and to completely abstain from eating at other times. The participants were not given any specific instructions regarding caloric or macronutrient intake.

At baseline, participants had a mean weight of 99.2 kg. Their mean age was 46.5 years and 60.3% were men. At the end of the 12 weeks, those in the time-restricted eating group (n = 59) did have a significant decrease in weight compared with baseline (−0.94 kg; = .01), while weight loss in the consistent meal group (n = 57) was not significant (−0.68 kg; P = .07). The difference in weight loss between the groups was not significant (−0.26 kg; = .63).

There were no significant differences in secondary outcomes of fasting insulin, glucose, A1c, or blood lipids within or between the time-restricted eating and consistent meal timing group either.