Plasma leptin and insulin levels in weight-reduced obese women with normalbody mass index - Relationships with body composition and insulin

Obesity is a complex disease with multiple features that has confounded eff orts to unravel its pathophysiology. As a means of distinguishing primary f rom secondary characteristics, we compared levels of fasting plasma leptin and insulin in a cohort of weight-reduced obese women who have attained and maintained a normal BMI for more than 1 year with the levels in cohorts of never-obese and currently obese women. Weight-reduced obese women showed d ecreased plasma concentrations of leptin and insulin compared with obese wo men, but these levels remained significantly higher than those of never-obe se women. Plasma leptin levels were highly correlated with plasma insulin l evels (r = 0.80, P < 0.001). To further explore relationships with body com position, total body fat was determined by dual-energy X-ray absorptiometry and body fat distribution by computed tomography in subsets of these group s. Weight-reduced obese women had a significantly greater percent body fat and subcutaneous abdominal fat mass than did the never-obese women, and the se were highly correlated with plasma leptin (r = 0.90, P < 0.001, and r = 0.52, P < 0.001, respectively). In these weight-reduced obese women, viscer al fat mass was similar to that of the never-obese. The insulin sensitivity index and first-phase insulin response were also comparable. These results demonstrate that higher leptin levels in weight-reduced obese women are re lated to the higher total fat and particularly the subcutaneous fat masses. Normalization of visceral fat mass in the weight-reduced obese was accompa nied by normalization of insulin sensitivity index and first-phase insulin response. This study suggests that increases in plasma leptin and insulin i n obesity are secondary features of the obese state.