Effect of time restricted eating on body weight and fasting glucose in participants with obesity: results of a randomized, controlled, virtual clinical trial.

ABSTRACT

BACKGROUND: Time restricted eating (TRE) is an emerging dietary intervention for weight loss that is hypothesized to reinforce the metabolic benefits of nightly fasting/ketosis. This pilot study investigated the effectiveness of a daily 14-h metabolic fast (1410 TRE beginning after dinner, a "fasting snack" at hour 12, and ending with breakfast 14 h later) combined with a commercial weight management program on body weight and fasting blood glucose (FBG) in individuals with obesity. We also investigated the effect of the low-calorie, high-fat, low-carbohydrate, and low-protein "fasting snack" on blood glucose. METHODS: This 8-week, randomized, controlled, clinical trial included men and women (BMI ≥ 30 kg/m2) between June and October 2020. Study procedures were conducted remotely. Participants were randomized to 1410 or 12-h TRE (1212, active comparator) and prescribed a diet (controlled for calories and macronutrient composition) and exercise program that included weekly customized counseling and support. The primary outcome was change from baseline in body weight in the 1410 group. RESULTS: Of the 78 randomized participants, 60 (n = 30/group) completed 8 weeks. The LS mean change from baseline in weight in the 1410 group was -8.5% (95% CI -9.6 to -7.4; P < 0.001) and -7.1% (-8.3 to -5.8; P < 0.001) in the 1212 group (between group difference -1.4%; -2.7 to -0.2; P < 0.05). There was a statistically significant LS mean change from baseline to week 8 in FBG in the 1410 group of -7.6 mg/dl (95% CI -15.1 to -0.1; P < 0.05) but not in the 1212 group (-3.1 mg/dl, -10.0 to 3.7; P = NS). Both interventions resulted in a larger reduction in FBG in participants with elevated FBG (≥100 mg/dl) at baseline (both P < 0.05). CONCLUSIONS: In participants with obesity who completed 8 weeks of the 1410 TRE schedule combined with a commercial weight loss program, there was statistically significant and clinically meaningful weight loss and improvements in FBG.