INS and polycystic ovary syndrome: Whereas the degree of IR in PCOS is greater than that predicted by BMI alone, nearly half of PCOS women are not obese [129] and the degree of visceral adiposity alone is inadequate to explain differences in insulin sensitivity between PCOS and normal women, suggesting that weight loss by itself may be insufficient to improve ovarian function in the sub-population of lean women with PCOS[130].