Obesity in women is closely linked to metabolic and circadian disruption. Melatonin has emerged as a potential adjunct therapy for improving obesity-related outcomes, yet evidence specific to women has been inconsistent. This systematic review and meta-analysis evaluated the effects of melatonin supplementation on anthropometric and glycemic indices in women with overweight and obesity. PubMed/MEDLINE, Web of Science, Scopus, Embase, and the Cochrane Library (CENTRAL), were searched through April 2025. Random-effects models generated weighted mean differences (WMDs) with 95% confidence intervals (CIs). Fourteen trials were included. Melatonin produced a significant reduction in body mass index (BMI) (WMD: − 1.03 kg/m²; 95% CI: − 2.23 to − 0.16; p < 0.001), with stronger effects in studies ≥ 12 weeks, using ≥ 6 mg/day, or involving participants with baseline BMI ≥ 30 kg/m². Melatonin significantly improved glycemic markers: fasting blood sugar (WMD: − 1.89 mg/dL; 95% CI: − 3.56 to − 0.22; p = 0.026), insulin (WMD: − 2.05 uIU/mL; 95% CI: − 3.69 to − 0.40; p = 0.015), and HOMA-IR (WMD: − 0.54; 95% CI: − 1.04 to − 0.03; p = 0.036). However, melatonin supplementation did not significantly affect body weight (WMD: − 0.34 kg; 95% CI: − 2.34 to 1.66; p = 0.737) or waist circumference (WMD: − 0.66 cm; 95% CI: − 3.75 to 2.43; p = 0.676). Melatonin supplementation modestly reduces BMI and significantly improves fasting glucose, insulin levels, and insulin resistance in women with overweight and obesity. No significant effects were observed on body weight or waist circumference. These findings suggest that melatonin may serve as a complementary strategy for improving metabolic parameters, particularly glycemic control.
Li et al. (Wed,) studied this question.