Time to Eat: Effects of Personalized Regular Meal Schedules on Body Weight and Mental and Physical Well-Being - A Randomized Controlled Pilot Trial

Background: Circadian disruption is associated with metabolic and mental health disturbances, but whether increasing meal regularity can reduce body weight and improve well-being without prescribed dietary restriction is unclear. Objective: To test the effects of personalized regular meal schedules on body weight and well-being in adults with body mass index (BMI) [&ge;]22 kg/m2. Methods: In this single-center randomized controlled pilot trial, 121 adults were assigned 2:1 to personalized meal schedules derived from 2 weeks of app-based dietary records or to a minimal-intervention control using a self-selected 18-hour eating window. The intervention lasted 6 weeks. One hundred participants completed the trial and were included in the primary analysis. Models adjusted for baseline BMI, age, sex, and, for non-weight outcomes, the corresponding baseline value. Results: Compared with controls, the intervention group had greater reductions in body weight (adjusted difference, -2.10 kg; 95% CI: -2.86, -1.34; P < 0.0001) and BMI (-0.70 kg/m2; 95% CI: -0.94, -0.45; P < 0.0001). Meal timing variability decreased substantially (-2.72 points; 95% CI: -3.13, -2.30; P < 0.0001), and greater improvements in regularity were associated with greater weight loss. Weight change was not associated with self-reported changes in energy intake or macronutrient composition. Among well-being outcomes, sleep quality showed the clearest adjusted between-group improvement (Pittsburgh Sleep Quality Index: -1.47 points; -2.28, -0.65; P = 0.0006). Conclusions: Personalized regular meal schedules reduced body weight and were accompanied by improvements in well-being, most clearly sleep quality. Larger trials using objective metabolic and circadian measures are needed to confirm clinical utility and clarify mechanisms. Trial registration: German Clinical Trials Register, DRKS00021419, registered August 21, 2020; https://drks.de/search/en/trial/DRKS00021419.