(P15-009-23) Effects of Time-Restricted Eating Combined With Exercise on Body Composition: A Systematic Review and Meta-Analysis

Objectives: The objective of this systematic review and meta-analysis was to determine if the combination of time-restricted eating (TRE) and exercise improves body composition compared to exercise alone in healthy adults.

Methods: A comprehensive literature search was conducted using five databases, including EBSCOhost (CINAHL, MEDLINE, SPORTDISCUS), PubMed, and SCOPUS from 2011 to January 31, 2023. Only human studies of either randomized controlled trials or randomized crossover designs that reported the effect of TRE in combination with exercise on body composition outcomes, including fat-free mass (FFM) (kg), body fat percentage (BF%), or fat mass (FM) (kg) compared to a non-TRE, exercise-matched control were considered. Only healthy adults (≥ 18 years) and interventions lasting ≥ 4 weeks were included. Fasting durations < 12 hours or other forms of intermittent fasting were excluded. Overall, 36 effect sizes (ES) from fourteen studies, including 339 participants were analyzed using a random-effects model to calculate standardized mean differences in ES, with 95% confidence intervals.

Results: TRE had a significant effect on FM (ES = -0.20; 95% CI = -0.28 to -0.12, p < 0.001) and BF% (ES = -0.24; 95% CI = -0.37 to -0.10, p < 0.001) relative to non-TRE control, without significant effects on FFM (ES = -0.03, 95% CI = -0.09 to 0.03; p = 0.29). Furthermore, the subgroup analysis did not find any significant impact of moderator variables, including age, body mass index (BMI), exercise type, study duration, and energy intake, on the variation in effect size (p > 0.05). Notably, the subgroups with BMI < 25 kg/m² (ES = -0.26; p < 0.001), aerobic exercise (ES = -0.33; p < 0.001), study duration ≥ 8 weeks (ES = -0.24; p < 0.001), and when TRE was in a calorie deficit compared to control (ES = -0.27; p < 0.05) had the most significant effects on FM.

Conclusions: According to the present systematic review and meta-analysis, TRE in combination with exercise may reduce FM and BF% compared to non-TRE, exercising control, while preserving FFM. Thus, TRE with exercise may have a role in improving body composition.

Funding Sources: Dean’s Office of the School of Applied Sciences and Startup funds from the University of Mississippi