Effects of high-protein diets on the cardiometabolic factors and reproductive hormones of women with polycystic ovary syndrome: a systematic review and meta-analysis.

The optimal dietary regimen for polycystic ovary syndrome (PCOS) has not been identified. High-protein diets (HPDs) are effective for weight control in individuals with metabolic abnormalities, but no systematic meta-analyses have yet summarised the effects of HPDs on PCOS. Seven electronic databases were searched from inception to 30 April 2023, and studies comparing the effects of HPDs and other diets on the anthropometrics, metabolic factors, and hormonal profiles for PCOS were identified. Data were pooled using random-effects models and expressed as weighted mean differences and 95% confidence intervals. The risk of bias was assessed by Cochrane Collaboration tool. Eight trials involving 300 women with PCOS were included. Compared with isocaloric balanced diets (BDs), HPDs significantly reduced fasting insulin (-2.69 μIU/mL, 95% CI [-3.81, -1.57], P < 0.0001, I 2  = 46%) and homoeostatic model assessment for insulin resistance (HOMA-IR-0.41, 95% CI [-0.80, -0.02], P = 0.04, I 2  = 94%) in women with PCOS. However, HPDs and BDs had comparable effects on weight loss, abdominal adiposity, lipid profiles, and reproductive hormones (all P ≥ 0.05). HPDs may benefit women with PCOS in terms of improving insulin resistance, supporting for their use as one of the dietary management options for PCOS, however further RCTs in larger and broader settings are required to confirm these observations and investigate the mechanism behind it.