Effects of Aerobic Exercise on Endogenous Estrogens and Body Composition in Women with Overweight or Obesity: A Systematic Review and Meta-Analysis.

Purpose: Overweight and obesity may alter endogenous estrogen exposure in women, yet evidence on the effects of aerobic exercise alone remains limited. This systematic review and meta-analysis aimed to evaluate the effects of aerobic exercise on endogenous estrogen profiles and body composition in adult women with overweight or obesity. Methods: We systematically searched PubMed, Web of Science, Scopus, Embase, and the Cochrane Library for randomized controlled trials involving women aged ≥ 18 years with BMI ≥ 25 kg/m2 who received aerobic exercise or aerobic exercise-based interventions. Random-effects meta-analyses used the DerSimonian-Laird estimator with Hartung-Knapp adjustment; subgroup analyses, meta-regression, sensitivity analyses, publication-bias assessment, and GRADE were also performed. Results: Fifteen trials involving 1217 participants were included. Aerobic exercise was associated with lower E2 (Hedges' g = -0.22, 95% CI -0.38 to -0.06, p < 0.05), E1 (g = -0.19, 95% CI -0.33 to -0.04, p < 0.05), and free E2 (g = -0.18, 95% CI -0.33 to -0.04, p < 0.05), and with higher SHBG (g = 0.49, 95% CI 0.06 to 0.92, p < 0.05). Aerobic exercise was also associated with reductions in body weight (MD = -3.06, 95% CI -4.60 to -1.51, p < 0.05), BMI (MD = -1.48, 95% CI -2.91 to -0.06, p < 0.05), waist circumference (MD = -2.50, 95% CI -3.59 to -1.41, p < 0.05), and total fat mass (MD = -2.30, 95% CI -3.48 to -1.12, p < 0.05). Heterogeneity was substantial for several outcomes, and the certainty of evidence ranged from moderate to very low. Conclusions: These findings suggest that aerobic exercise may be associated with changes in estrogen bioavailability and reductions in body composition measures, but the evidence remains preliminary.