Exercise Timing and its Effects on Eating Behavior, Weight, and Body Composition: A Systematic Scoping Review to Identify Gaps and Inform Future Research

Purpose: This scoping review aims to: (1) describe the existing evidence and, based on that, examine study designs, intervention strategies, participant characteristics (e.g., age, sex), and exercise protocols (e.g., modality, intensity, duration); (2) Identify knowledge gaps related to the effects of exercise timing, and provide recommendations for future research directions. Results: Fragmented evidence of time-of-day effects was identified across acute studies, particularly for subjective appetite ratings, food preference, energy intake, and relative energy intake. In chronic studies, isolated findings were observed for weight loss, fat mass, and macronutrient intake. Overall, results across both acute and chronic studies were inconsistent. Conclusions: Future research could benefit from greater inclusion of females with appropriate menstrual-cycle control, wider use of control trials, and more comprehensive measurement of energy expenditure. Coordinated studies that systematically vary exercise intensity and duration are needed to clarify acute timing effects. In chronic studies, interventions may consider higher training volume, longer duration, or acute protocols previously shown to produce timing effects, alongside consistent monitoring of eating and physical-activity behaviors and careful seasonal balance. Whether exercise timing influences daily routines or dieting trends also remains to be clarified.