Abstract
Polycystic ovary syndrome (PCOS) is a common endocrine disorder frequently complicated by obesity, insulin resistance, and reproductive dysfunction. The ketogenic diet (KD), characterized by very low carbohydrate intake, has emerged as a potential intervention, but its comprehensive short-term effects in this population require synthesis. This systematic review evaluates the impact of KD on metabolic, hormonal, and reproductive outcomes in overweight and obese women with PCOS. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines, a systematic search of multiple databases was conducted for studies published up to 2024. Randomized controlled trials (RCTs), comparative studies, and prospective cohorts assessing a KD (≤50 g carbohydrates/day) over 6-24 weeks in overweight/obese women with PCOS were included. Fourteen studies involving 643 participants (n = 240 from RCTs; n = 403 from observational or single-arm studies) were analyzed. Most studies reported significant weight loss (7-13% of baseline weight) and reduced visceral adiposity. Marked improvements were observed in insulin sensitivity, with reductions in fasting insulin, glucose, and homeostatic model assessment of insulin resistance (HOMA-IR). Hormonal profiles improved, evidenced by decreased total and free testosterone, increased sex hormone-binding globulin (SHBG), and normalization of the LH/FSH ratio. Reproductive benefits, including restored menstrual regularity and increased ovulation rates, were reported, although pregnancy outcomes were derived from small, uncontrolled cohorts and should be interpreted cautiously. Lipid profile changes were mixed but generally favorable, and adverse events were typically mild, though adherence challenges were noted. Low-to-moderate certainty evidence suggests that KD demonstrates significant short-term efficacy for improving weight, metabolic parameters, androgen excess, and reproductive function in overweight/obese women with PCOS. However, the evidence is limited by study heterogeneity, short durations, and varied protocols. These findings support KD as a promising therapeutic option, but larger, long-term RCTs are needed to establish its safety, sustainability, and optimal implementation within PCOS management.