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.