Time-Restricted Eating Effects on Body Composition and Metabolic Measures in Humans who are Overweight: A Feasibility Study

Objective: In contrast to intentionally restricting energy intake, restricting the eating window may be an option for treating obesity. By comparing time-restricted eating (TRE) with an unrestricted (non-TRE) control, it was hypothesized that TRE facilitates weight loss, alters body composition, and improves metabolic measures. Methods: Participants (17 women and 3 men; mean [SD]: 45.5 [12.1] years; BMI 34.1 [7.5] kg/m²) with a prolonged eating window (15.4 [0.9] hours) were randomized to TRE (n = 11: 8-hour window, unrestricted eating within window) versus non-TRE (n = 9: unrestricted eating) for 12 weeks. Weight, body composition (dual x-ray absorptiometry), lipids, blood pressure, 2-hour oral glucose tolerance, 2-week continuous glucose monitoring, and 2-week physical activity (actigraphy assessed) were measured during the pre- and end-intervention periods. Results: The TRE group significantly reduced the eating window (end-intervention window: 9.9 [2.0] hours) compared with the non-TRE group (end-intervention window: 15.1 [1.1] hours) (P < 0.01). Compared with non-TRE, TRE decreased the number of eating occasions, weight, lean mass, and visceral fat (all P ≤ 0.05). Compared with preintervention measures, the TRE group reduced the number of eating occasions (−21.9% [30.1%]) and reduced weight (−3.7% [1.8%]), fat mass (−4% [2.9%]), lean mass (−3.0% [2.7%]), and visceral fat (−11.1% [13.4%]) (all P ≤ 0.05). Physical activity and metabolic measures remained unchanged. Conclusions: In the setting of a randomized trial, TRE presents a simplified view of food intake that reduces weight.