The long-term effectiveness and safety of time-restricted eating for weight loss is not clear.
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We randomly assigned 139 obese patients to time-restricted eating (eating only between 8:00 and 4:00 p.m.) with calorie restriction or daily calorie restriction alone. For 12 months, all participants were instructed to follow a calorie-restricted diet consisting of 1500 to 1800 kcal per day for men and 1200 to 1500 kcal per day for women. The primary outcome was the difference between the two groups in the change from baseline in body weight; secondary outcomes included changes in waist circumference, body mass index (BMI), amount of body fat, and measures of metabolic risk factors.
Of the total 139 participants who underwent randomization, 118 (84.9%) completed the 12-month follow-up visit. The mean weight loss from baseline at 12 months was -8.0 kg (95% confidence interval) [CI], -9.6 to -6.4) in the time-restriction group and -6.3 kg (95% CI, -7.8 to -4.7) in the daily-calorie restriction group. Changes in weight were not significantly different in the two groups at the 12-month assessment (net difference, -1.8 kg; 95% CI, -4.0 to 0.4; P=0.11). Results of analyzes of waist circumference, BMI, body fat, body lean mass, blood pressure, and metabolic risk factors were consistent with the results of the primary outcome. In addition, there were no significant differences between the groups in the number of adverse events.
Among patients with obesity, a regimen of time-restricted eating was no more beneficial than daily caloric restriction with respect to reductions in body weight, body fat, or metabolic risk factors. (Funded by the National Key Research and Development Project [No. 2018YFA0800404] and others; ClinicalTrials.gov number, NCT03745612.)