Leptin responses to weight loss in postmenopausal women: relationship to sex-hormone binding globulin and visceral obesity.

Abstract

Leptin concentrations increase with obesity and tend to decrease with weight loss. However, there is large variation in the response of serum leptin levels to decreases in body weight. This study examines which endocrine and body composition factors are related to changes in leptin concentrations following weight loss in obese, postmenopausal women. Body composition (DXA), visceral obesity (computed tomography), leptin, cortisol, insulin, and sex hormone-binding globulin (SHBG) concentrations were measured in 54 obese (body mass index [BMI] = 32.0+/-4.5 kg/m2; mean +/- SD), women (60+/-6 years) before and after a 6-month hypocaloric diet (250 to 350 kcal/day deficit). Body weight decreased by 5.8+/-3.4 kg (7.1%) and leptin levels decreased by 6.6+/-11.9 ng/mL (14.5%) after the 6-month treatment. Insulin levels decreased 10% (p< 0.05), but mean SHBG and cortisol levels did not change significantly. Relative changes in leptin with weight loss correlated positively with relative changes in body weight (r = 0.50, p<0.0001), fat mass (r = 0.38, p<0.01), subcutaneous fat area (r = 0.52, p<0.0001), and with baseline values of SHBG (r = 0.38, p<0.01) and baseline intra-abdominal fat area (r = -0.27, p<0.06). Stepwise multiple regression analysis showed that baseline SHBG levels (r2 = 0.24, p<0.01), relative changes in body weight (cumulative r2 = 0.40, p<0.05), and baseline intra-abdominal fat area (cumulative r2 = 0.48, p<0.05) were the only independent predictors of the relative change in leptin, accounting for 48% of the variance. These results suggest that obese, postmenopausal women with a lower initial SHBG and more visceral obesity have a greater decrease in leptin with weight loss, independent of the amount of weight lost.