Objective  To explore the effects of ketogenic diet on serum vitamin D and glycolipid metabolism in overweight or obese patients with polycystic ovary syndrome (PCOS).

  Methods  A total of 51 overweight or obese patients with PCOS from June to December 2021 in the gynecological clinic of Beijing Shijitan Hospital Affiliated to Capital Medical University were selected and conducted with ketogenic diet intervention for 4 weeks. Changes of body weight, vitamin D and glycolipid metabolism indexes before and after the intervention were compared in all the patients.

  Results  After 4 weeks of ketogenic diet intervention, the level of vitamin D significantly increased from (16.37±5.67) ng/mL to (21.72±6.64) ng/mL, and the proportion of insufficient or deficient vitamin D significantly decreased from 82.35% to 45.10% in all the patients (P < 0.01); body composition analysis showed that the body mass (81.11±11.23) kg versus (75.32±10.58) kg, body mass index(29.87± 3.79) kg/m² versus (27.75±3.68) kg/m², body fat rate (40.77±4.70)% versus (37.88±5.14)%, visceral fat area (163.25±38.76) cm² versus (142.56±39.53) cm² and waist hip ratio (0.96±0.05) versus (0.94±0.06) decreased significantly (P < 0.01); the indexes of glycolipid metabolism showed that fasting blood glucose (18.59±8.86) μIU/mL versus (11.43±4.90) μIU/mL, fasting insulin (5.57±1.90) mmol/L versus (4.90±0.78) mmol/L, insulin resistance index (4.62±2.55) versus (2.52±1.20), glycosylated hemoglobin (5.70±1.06)% versus (5.24±0.63)%, triglyceride (1.68±0.86) mmol/L versus (1.07±0.33) mmol/L, high density lipoprotein (1.22±0.25) mmol/L versus (1.07±0.21) mmol/L decreased significantly in all the patients (P < 0.01), while the total cholesterol (4.98±1.09) mmol/L versus (4.80±0.91) mmol/L and low density lipoprotein (3.42±1.02) mmol/L versus (3.27±0.91) mmol/L showed no significant decrease (P>0.05). Before intervention, there was a significant negative correlation between vitamin D level and waist-hip ratio (r=-0.289, P=0.039); after the intervention, the level of vitamin D was significantly negatively correlated with waist-hip ratio, visceral fat area, fasting insulin and insulin resistance index in all the patients(r=-0.361, -0.279, -0.329 and -0.309, P < 0.05).

  Conclusion  Ketogenic diet can effectively reduce weight and improve vitamin D level and glycolipid metabolism at the same time, and there is a synergistic effect between vitamin D and glucose metabolism.