Objective To explore the early time-restricted feeding (e-TRF) on serum vitamin D level and glycolipid metabolism in overweight/obese patients with polycystic ovary syndrome (PCOS).

Methods A total of 35 overweight/obese patients with PCOS were publicly recruited for treatment of 4-week e-TRF dietary intervention in the body quality management clinic of authors' hospital. Before and after intervention, the human body composition analysis and blood sampling tests (serum vitamin D level and biochemical indicators related to glucose and lipid metabolism) were conducted, and changes in various indicators were compared.

Results After 4 weeks of e-TRF intervention, the level of vitamin D in 35 patients increased significantly, and the ratios of cases with vitamin D deficiency or insufficiency decreased significantly (P < 0.01). In the indicators of glucose and lipid metabolism, the levels of glycated hemoglobin, fasting blood glucose, fasting insulin, insulin resistance index, total cholesterol, triglycerides and low-density lipoprotein cholesterol decreased significantly after intervention when compared to those before intervention, while the level of high-density lipoprotein cholesterol increased significantly when compared to that intervention before (P < 0.05). After intervention, the vitamin D level was significantly negatively correlated with body weight, body mass index, hip circumference, fasting insulin, insulin resistance index and triglycerides (r=-0.451, -0.352, -0.424, -0.543, -0.491, -0.394, P < 0.05).

Conclusion The e-TRF can increase vitamin D level in overweight/obese patients with PCOS in a short period of time (4 weeks), reduce body mass, and improve glucose and lipid metabolism indicators.