(P15-019-23) Effects of Time-Restricted Eating on Calorie Intake and Body Weight in Free-Living Adults: A Systematic Review and Meta-Analysis

Objectives: While it is thought that time-restricted eating (TRE) may lead to calorie reduction, past research findings are inconsistent. Thus, a systematic review and meta-analysis was conducted to determine if TRE in free-living adults with ad-libitum intake results in calorie restriction with changes in body weight (BW).

Methods: A literature search for “time-restricted eating” in studies published between January 1, 2012 and January 31, 2023 was done using the following database: PubMed, CINAHL, MEDLINE, Scopus, and SPORTDiscus. Inclusion criteria were: a) randomized controlled or randomized crossover studies; b) study duration of > 4 weeks; c) ad-libitum intake; d) without chronic conditions that may affect the study's outcomes; e) pre-post data for both outcomes; f) age 18 years. Effect sizes (ES) were reported as standardized mean differences (SMD) and 95% confidence intervals (CI). The prediction interval was also computed. Moderator analyses were performed using the mean age of participants, sex, mean BMI, intervention length, and fasting duration. Statistical analyses were performed using IBM SPSS Statistics (version 29.0).

Results: Twelve studies (24 effect sizes) with 283 subjects were entered into the analysis. TRE resulted in significant decreases in calorie intake (ES: -0.387, 95% CI: -0.627 to -0.140, p= 0.002; I²=34.6%) and BW (ES: -0.208, 95% CI: -0.274 to -0.143, p< 0.001; I²= 0%) compared to the control group. For calorie intake, the prediction interval was -1.011 to 0.237 showing that true ES could be -1.011 in some populations and 0.237 in others. Regarding BW, the prediction interval was -0.278 to -0.137 showing that true ES could be -0.278 in some populations and -0.137 in others. Based on moderator analyses, overall ES was not affected by any moderator variables except sex (Qbetween = 6.625; P = .01) for calorie intake. Studies consisting of 50% of women showed significantly greater ES (-0.587), compared to studies consisting of < 50% of women (ES: -0.041).

Conclusions: TRE may cause significant reductions in daily calorie intake and BW compared to control groups, even when ad-libitum food intake is allowed with TRE.

Funding Sources: Startup funds and research support by the Dean’s Office of the School of Applied Sciences, University of Mississippi.