Nutrients · Oct 29, 2026
Is Earlier Always Better? Early Versus Later Time-Restricted Eating, Body Composition, and Exercise Performance: A Narrative Review
By Yu Z, Ueda T, Zhou P
Background: Time-restricted eating (TRE) confines daily food intake to a consistent window that may occur early (eTRE) or later in the day (delayed TRE, dTRE). Whether timing differentially affects body composition and exercise performance, and whether exercise training modifies these effects, remains unclear. Methods: PubMed, Google Scholar, and reference lists were searched. Twenty-three intervention studies were narratively synthesized by timing comparison and exercise context, with study-level methodological appraisal. Results: Eight studies directly compared earlier and later windows. None favored the later window for body composition. Greater weight or fat loss with eTRE came from one crossover trial and two non-randomized comparisons, whereas the randomized parallel-group trials, including the largest, detected no difference. With structured training, TRE reduced fat mass more than training alone in four of six trials, regardless of window type; lean-mass comparisons were imprecise. No direct comparison detected timing differences in strength, muscular endurance, or aerobic outcomes, but estimates were imprecise. Greater sprint power after dTRE in one crossover trial may reflect test-day feeding, learning, or order effects. Conclusions: Earlier eating was not consistently better, but timing cannot be considered irrelevant. Trials crossing window timing with controlled energy intake and matched training are needed.