A study found that a ketogenic diet improved menstrual cycles, ovarian health and hormone balance in women with PCOS, even without weight loss.
By
Lana Pine
| Published on January 29, 2025
5 min read
Credit: Adobe Stock/julie208
A ketogenic diet followed by a gradual reintroduction of carbohydrates was shown to improve menstrual cycle regularity, among other benefits, in women with polycystic ovary syndrome (PCOS).
PCOS is a hormonal condition that affects many women of reproductive age. The heterogeneity of its presentation, including weight issues, complicates the management of the condition because while many women with PCOS experience weight gain, some do not. Therefore, the pharmacological treatments and lifestyle modification suggestions may not apply to those with normal body weight, thus creating a gap in treatment options.
“Given the limitations of existing treatments that often focus on weight management, there is a pressing need for alternative therapeutic strategies to address the underlying issues of PCOS more comprehensively,” wrote a team of Italian investigators led by Rebecca Rossetti, M.D., associated with the Department of Experimental Medicine, Section of Medical Pathophysiology, Food Science and Endocrinology at Sapienza University of Rome, Italy.
Some research has suggested that a ketogenic diet, which is very low in carbohydrates, might help manage PCOS symptoms by improving insulin sensitivity and reducing body weight.
The prospective, longitudinal study followed 18 women with PCOS treated at the Endocrinology and Gynecology units of Policlinico Universitario Umberto I in Rome for six months to see how a ketogenic diet affected their condition. Among these patients, 28% were normal weight, 28% were overweight, and 44% had obesity. Eligibility criteria included women of fertile age, a PCOS diagnosis and an average menstrual cycle longer than 35 days (oligomenorrhea).
Assessments were performed at baseline and six months and included anthropometric data, a pelvic ultrasound, blood chemistry, body composition, hirsutism and menstrual cycle frequency.
Participants followed a strict ketogenic diet for 45 days, slowly reintroduced carbohydrates over another 45 days, and finally transitioned to general healthy eating. The diet involved a carbohydrate intake of less than 50 grams and a daily protein intake of 1.3 to 1.4 grams per kilogram, with the remaining calories coming from fats. These patients were also advised to drink 2 liters of water per day and were provided with vitamin and mineral supplement suggestions. After the ketogenic diet period, participants slowly incorporated fruits and pulses (such as peas, lentils, chickpeas and beans) and were allowed to consume bread and rice occasionally. The reintroduction period was designed to avoid the unfavorable effects of a rapid reintroduction to carbohydrates.
Twelve women completed the study with an average age of 26 years and an average cycle duration of 45 days. At six months, patients saw significant weight loss and a significant reduction in waist and hip circumference.
The results demonstrated that the ketogenic diet improved menstrual cycle regularity, ovarian health and hormone levels regardless of whether patients lost weight. The diet led to improvements in the lipid profile, reductions in body fat and visceral fat, and improved insulin resistance. During this time, the length of menstrual cycles dropped from an average of 45 days to an average of 32 days.
While some findings were not associated with weight loss, improvements in testosterone levels and symptoms like excessive hair growth (hirsutism) were linked to weight and fat loss. Findings suggest that a ketogenic diet could benefit women with PCOS even if they are not trying to lose weight, likely due to the effects of ketosis itself.
No significant adverse events were observed throughout the study period, although some participants reported mild constipation that lasted for a few days.
Investigators noted the small sample size, lack of control group and low percentage of normal-weight patients as limitations of the study.
“Our study adds to this body of evidence by demonstrating significant improvements in PCOS-related outcomes as well as anthropometric characteristics following a ketogenic diet in both lean and overweight women with PCOS,” they concluded.