Efficacy of Early vs. Late Time-Restricted Eating in Adolescents with Obesity: A Randomized Clinical Trial

Introduction and Objective: Time-restricted eating (TRE) has emerged as a simple, low-cost intervention; however, it is unclear whether the timing of the eating window influences effectiveness. This study compared the effectiveness of late TRE (lTRE) versus early TRE (eTRE) in reducing percent of the 95th percentile for body mass index (%BMIp95) at 24 weeks in youth with obesity. Methods: This randomized, parallel-group clinical trial was conducted at a single safety-net children’s hospital. Adolescents aged 12 to 20 years with obesity were randomized 1:1 to eTRE (07:00-15:00) or lTRE (12:00-20:00). All participants were instructed to consume their daily caloric intake within an assigned 8-hour eating window without prescribed caloric restriction. Adherence was assessed using daily eating logs and three wear periods of continuous glucose monitoring. The primary outcome was change in %BMIp95 at 24 weeks. Secondary outcomes included eating behaviors, sleep quality, metabolic markers, and body composition. Analyses followed the intention-to-treat principle using linear mixed-effects models. Results: Among 94 randomized youth (median [Q1, Q3] age, 15.9 [13.8-17.8] years; 51% female; 86% Hispanic), 80 (85%) completed 24-week assessments. Adherence was high (mean, 5.0 days/week for eTRE vs 6.0 days/week for lTRE). At 24 weeks, %BMIp95 decreased in both groups (eTRE, −4.6%; 95% CI, −6.4% to −2.9%; lTRE, −2.8%; 95% CI, −4.6% to −1.1%). The between-group difference (lTRE − eTRE) was 1.84% (95% CI, −0.21 to 3.88). No significant between-group differences were observed in sleep, metabolic markers, or caloric intake. Both groups demonstrated significant within-group improvements in food responsiveness. Conclusion: In this randomized clinical trial, both early and late TRE were feasible and associated with reductions in excess adiposity among adolescents with obesity. Early TRE produced numerically greater reductions in %BMIp95, but differences between groups were not statistically significant. Disclosure: J.A. Bakhsh: None. M.H. Vu: None. S. Salvy: None. K. Varady: None. J. Raymond: None. A.P. Vidmar: Research Support; Ended; Dexcom, Inc. Research Support; Current; Lilly. Advisory Panel; Ended; Rhythm Pharmaceuticals, Inc. Advisory Panel; Current; Soleno Therapeutics, Inc. Research Support; Current; Rhythm Pharmaceuticals, Inc., Soleno Therapeutics, Inc. Funding: American Diabetes Association (11-22-ICTSN-32), K23DK134801 NIH NIDDK