Ketogenic diet improves fertility in patients with polycystic ovary syndrome: A brief report Original paper

What was studied?

This retrospective study examined the effects of a ketogenic diet (KD) on menstrual regularity and pregnancy rates in women with polycystic ovary syndrome (PCOS). Conducted at the Cleveland Clinic, the study evaluated 30 women diagnosed with PCOS who followed a KD for at least three months as part of a multidisciplinary weight management program. The objective was to determine whether KD could restore ovulatory function and improve fertility, particularly in the context of insulin resistance, obesity, and hyperandrogenism that characterize PCOS.

Who was studied?

The study population included 30 women with PCOS and obesity, aged around 31 years. All participants were enrolled in a structured program that combined nutritional counseling, exercise guidance, and endocrine evaluation. Among them, 18 desired pregnancy, and some were concurrently using metformin or ovulation induction agents. Importantly, participants had no other major endocrine or metabolic conditions, ensuring the focus remained on PCOS-related infertility. The KD protocol restricted daily carbohydrate intake to ≤20g, moderate protein based on weight, and up to 40g of fat, with calorie intake ranging from 1000–1200 kcal/day.

What were the most important findings?

The ketogenic diet led to complete restoration of regular menstrual cycles in all participants with irregular periods, with 92% achieving this within six months. Among those desiring pregnancy, 55.6% (10) became pregnant, five without any ovulation induction or metformin. Women in the non-metformin group had a 100% pregnancy rate, compared to 38.5% in the metformin group. Importantly, there was no statistically significant difference in weight loss between those who conceived and those who did not, suggesting that mechanisms beyond weight reduction, such as improved insulin sensitivity, may be central to the fertility benefits observed. While the study did not directly measure microbiome changes, the KD is known to influence microbial composition, particularly by reducing pro-inflammatory species and enhancing Akkermansia muciniphila and SCFA-producing microbes such as Bacteroides and Faecalibacterium prausnitzii. These microbial shifts are closely associated with improved insulin signaling, reduced systemic inflammation, and improved endocrine profiles—all relevant in PCOS.

What are the implications of this study?

This study provides compelling evidence that the ketogenic diet can be a highly effective non-pharmacologic intervention for improving fertility in women with PCOS. By normalizing menstrual cycles and significantly improving pregnancy rates, especially among those not on pharmacologic ovulation aids, the KD presents a viable alternative or adjunct to current fertility treatments. The results suggest that mechanisms like enhanced insulin sensitivity and reduced inflammatory signaling play a greater role than weight loss alone. For clinicians, the KD offers a microbiome-relevant strategy that addresses the root metabolic and endocrine disturbances of PCOS. Given its high efficacy in restoring ovulation and supporting conception, especially in obese patients with insulin resistance, KD merits consideration in personalized fertility management plans. Larger prospective studies are now needed to further investigate long-term outcomes, microbiome shifts, and to standardize KD protocols for PCOS patients.