The Impact of Exercise Timing on Energy Intake: A Systematic Review and Meta-Analysis of Diurnal and Meal Timing Effects.

This systematic review and meta-analysis examine the literature (up to August 2^nd 2024) on the influence of exercise timing on energy intake in both children and adults. A comprehensive search was conducted using MEDLINE, EMBASE, Cochrane Library, SPORTDiscus, and Web of Science Core Collection, following PRISMA guidelines. The review was registered in Prospero (CRD42024553381) and evaluated using QUADAS-2. From an initial 3,276 articles, a meta-analysis (six studies) revealed that daily energy intake was not significantly lower when exercise was performed in the morning versus the afternoon/evening: mean difference of 64±77 kcal (95% CI: -86 to 215 kcal; p=0.403). A meta-analysis (three studies, all with children) comparing lunch energy intake before versus after exercise showed a significant difference in energy intake when exercise was performed post-meal: (-39±13 kcal, 95% CI: -63 to -14 kcal; p = 0.002). For the meta-analysis of delayed lunch (five studies), where exercise ended 15 minutes to four hours before the meal, and the delay between the start of each exercise condition within the same study was typically around two hours, no significant difference in energy intake was found (-2±67 kcal; 95% CI: -134 to 130 kcal; p=0.977). Regarding chronic exercise, a decrease in energy intake was observed with evening exercise (one study), morning exercise (two studies) or independently of exercise timing (two studies). In conclusion, findings suggest acute exercise may reduce intake in children and adolescents, but this effect is dependent on the timing of exercise.