In women with polycystic ovarian syndrome (PCOS), hyperinsulinaemia stimulates ovarian cytochrome P450c17α activity that stimulates ovarian androgen production. The objective of this study was to compare whether timed caloric intake differentially influences insulin resistance and hyperandrogenism in lean PCOS women. A total of 60 lean PCOS women (BMI 23.5-24) were randomized into two isocaloric maintenance diets with different meal timing distribution: a breakfast diet of 980 kcal breakfast, 640 kcal lunch and 190 kcal dinner, or a dinner diet of 190 kcal breakfast, 640 kcal lunch and 980 kcal dinner for 90 days. In the breakfast diet group, a significant decrease was observed in both glucose area under the curse, insulin area under the curve by 7 and 54% respectively. In the breakfast group, free testosterone decreased by 50% and sex hormone-binding globulin increased by 105%. Gonadotropin-releasing hormone-stimulated peak serum 17OHP decreased by 39%. No change in these parameters was observed in the dinner group. Women in the breakfast group had an increased ovulation rate. In lean PCOS women, a high caloric intake at breakfast with reduced intake at dinner results in improved insulin sensitivity indices, which ameliorates hyperandrogenism and improves ovulation rate. Clin Sci (Lond). 2013 Nov. PMID: 23688334
