Effects of combining exercise with a 16:8 time-restricted eating protocol on body composition and glucose–lipid metabolism in adults: a systematic review and meta-analysis

Background: Time-restricted eating (TRE) has emerged as a promising nutritional strategy for improving metabolic health, yet its additive benefits when combined with structured exercise remain unclear. Objective: This systematic review and meta-analysis evaluated the effects of exercise combined with a 16:8 TRE protocol on body composition and glucose-lipid metabolism in adults. Methods: Following PRISMA guidelines and PROSPERO registration (CRD420251240058), eight electronic databases were searched through August 2025 for randomized and randomized crossover trials comparing exercise plus 16:8 TRE with exercise alone. Three reviewers independently performed study selection, data extraction, risk-of-bias assessment (ROB 2), and GRADE evaluation. Random-effects meta-analyses were conducted using R software. Subgroup analyses and meta-regression explored potential moderators. Results: Fifteen trials involving 511 participants were included. Compared with exercise alone, the combined intervention significantly reduced body weight (MD - 1.44 kg, 95% CI - 2.74 to -0.13) and fat mass (MD - 1.04 kg, 95% CI - 1.95 to -0.13). Significant improvements were also observed in triglycerides (SMD - 0.25, 95% CI - 0.45 to -0.06) and LDL cholesterol (SMD - 0.22, 95% CI - 0.37 to -0.08), while other body composition and glycemic markers showed no significant changes. Greater reductions in body weight and fat mass were observed when TRE was combined with aerobic exercise, and LDL-C reductions were more pronounced in men. Sensitivity analyses confirmed result robustness with minimal publication bias. Conclusion: Exercise combined with a 16:8 TRE protocol may confer small additional short-term benefits for body weight, fat mass, and selected lipid markers beyond exercise alone. However, the evidence base is limited by the small number of studies, modest sample sizes, and imbalance in participant characteristics across sex and metabolic status. These findings should therefore be interpreted cautiously.