Objective To observe the adverse reactions of ketogenic diet therapy in patients with polycystic ovary syndrome (PCOS).

Methods A total of 75 PCOS patients who started a ketogenic diet and adhered to follow-up from January to December 2023 in Beijing Shijitan Hospital Affiliated to Capital Medical University were selected as the research objects. The occurrence of adverse reactions from the start of the ketogenic diet to 6 months after its completion was followed up.

Results After implementing ketogenic diet intervention, the body weight, body fat percentage, visceral fat area, waist-to-hip ratio, body mass index, and incidence of menstrual disorders in PCOS patients decreased significantly from (84.50±12.85) kg, (41.87±5.25)%, (167.87±39.63) cm², (0.95±0.04), (31.71±5.29) kg/m², and 74.67% before intervention to (70.75±10.91) kg, (36.60±4.58)%, (122.78±36.94) cm², (0.90±0.04), (26.65±4.35) kg/m², and 21.33% after intervention (P＜0.05 or P＜0.01). The top three adverse reactions were hair loss (25.33%), sleep disturbances (16.00%), and weakness, dizziness and fatigue (13.33%). No new adverse reactions such as gallstones, urinary stones, hypoglycemia, or hypoalbuminemia were observed.

Conclusion Ketogenic diet therapy for PCOS patients exhibits relatively high safety with no severe adverse reactions, but attention should be paid to the relatively high incidence of hair loss.