Efficiency of time-restricted eating and energy restriction on anthropometrics and body composition in adults: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND: We examined the effect of time-restricted eating (TRE) alone and in combination with energy restriction (ER) on the body composition in adults. METHODS: PubMed, the Cochrane Library, EMBASE, Web of Science, and Scopus were systematically searched for articles that evaluated the effects of TRE or TRE + ER on body composition variables. Meta-analysis was performed to explore the overall effect of TRE on body composition. Subgroup analysis was performed to compare the changes in the TRE and TRE + ER trials with those in no restriction (NR) and ER trials. Intervention effects on body composition are expressed as weighted mean differences (WMDs) and 95% confidence intervals (CIs). RESULTS: A total of 20 randomized controlled trials (1242 participants) were included in the systematic review and meta-analysis. Pooled results showed that TRE significantly decreased body weight, fat mass, fat-free mass, body mass index (BMI) and waist circumference (WC). Subgroup analyses revealed that TRE alone (compared to NR) and TRE plus ER (compared to ER) considerably decreased body weight (TRE = WMD:-1.59 kg, 95%CI:-2.02 to -1.15 p < 0.00001; TRE + ER = WMD:-0.94 kg, 95%CI:-1.58 to -0.31, p = 0.004) and fat mass (TRE = WMD:-0.93 kg, 95%CI:-1.22 to -0.63, p < 0.00001; TRE + ER = WMD:-1.13 kg, 95%CI:-1.50 to -0.75, p < 0.00001) but not fat mass percentage. Both TRE and TRE + ER decreased fat-free mass (TRE = WMD:-0.58 kg, 95%CI:-0.81 to -0.36, p < 0.00001; TRE + ER = WMD:-0.56 kg, 95%CI:-0.81 to -0.31, p < 0.0001). TRE independently and combinedly decreased BMI (TRE = WMD:-0.63 kg/m2, 95%CI:-0.95 to -0.30, p = 0.0002; TRE + ER = WMD:-0.42 kg/m2, 95%CI:-0.78 to -0.07, p = 0.02) and WC (TRE = WMD:-2.11 cm, 95%CI:-3.35 to -0.86, p = 0.0009; TRE + ER = WMD:-2.20 cm, 95%CI: -2.64 to -1.75, p < 0.00001). CONCLUSIONS: TRE independently promotes weight loss in adults, and combining of TRE with ER has no additional beneficial effects on weight loss. TRIAL REGISTRATION: This study was registered with PROSPERO: CRD42022370215.