Effects of the very low-carbohydrate ketogenic diet in women with polycystic ovary syndrome: a systematic review with meta-analysis of clinical trials.

Polycystic ovary syndrome is a disorder characterised by insulin resistance, low-grade inflammation and increased adipose tissue. The very low-carbohydrate ketogenic diet has been suggested to reduce obesity risks in polycystic ovary syndrome. This study aimed to update the evidence on the effects of the very low-carbohydrate ketogenic diet in women with polycystic ovary syndrome. Searches were conducted in electronic databases for randomised clinical trials addressing the research question. The values for the meta-analysis were presented as weighted mean difference (WMD). Twelve studies were included in the qualitative analysis and eleven in the quantitative analysis. Significant reductions were observed in anthropometric outcomes: weight (WMD: -9·57 kg; P < 0·0001), waist circumference (WMD: -7·75 cm; P < 0·0009), fat body mass (WMD: -7·44 kg; P = 0·0008), BMI (WMD: -3·45 kg/m2; P < 0·0001) and waist-to-hip ratio (WMD: -0·02; P < 0·0034). Hormonal improvements included free testosterone (WMD: -0·31 ng/dl; P < 0·0001), total testosterone (WMD: -7·21 ng/dl; P < 0·0001), sex hormone-binding globulin (WMD: 15·22 nmol/l; P = 0·0035), luteinising hormone (WMD: -3·97 U/L; P = 0·0008) and luteinising hormone:follicle-stimulating hormone ratio (WMD: -1·04; P = 0·0053), but not for follicle-stimulating hormone levels (WMD: 1·23 mUI/ml; P = 0·12). Significant changes in metabolic markers were seen in blood glucose (WMD: -9·65 mg/dl; P = 0·0031), insulin (WMD: -2·41 mg/dl; P = 0·0387), homeostatic model assessment for insulin resistance (WMD: -2·46; P = 0·0123) and TAG (WMD: -29·95 mg/dl; P = 0·0188). The very low-carbohydrate ketogenic diet shows significant benefits in managing body composition, reducing hyperandrogenism, balancing sex hormones and improving glucose metabolism in polycystic ovary syndrome.