SERUM LEPTIN IN OBESITY IS RELATED TO GENDER AND BODY-FAT TOPOGRAPHY BUT DOES NOT PREDICT SUCCESSFUL WEIGHT-LOSS

Objective: Leptin is the product of the ob gene shown to regulate body fat and appetite in mice. Tt is produced by human adipose tissue also , but its physiological functions in man are poorly known. Study desig n and methods: We studied serum leptin concentrations in ten obese men and 35 obese women (age and body mass index 42 +/- 7 years and 35.1 /- 3.6 kg/m(2) respectively) before (baseline) and at 17 and 57 weeks during weight loss of 10.9% of the initial weight. Results: Serum lept in concentrations at baseline were 55% higher in women than in men (af ter adjustment for age and body fat mass, P = 0.002) and remained so d uring the follow-up. At baseline, serum leptin correlated with fat mas s (r = 0.60, P < 0.001) estimated by bioelectrical impedance, and the changes in leptin concentrations from baseline to week 17 correlated w ith the changes in fat mass (r = 0.73, P < 0.001), but baseline leptin levels were not predictive of the successful weight loss. Leptin conc entrations correlated with hip circumference (r = 0.49, P < 0.001 at b aseline adjusted for age and sex), but the correlation with waist circ umference became evident only during the weight loss (at week 57, r = 0.63, P < 0.001). Conclusions: Serum leptin concentrations are higher in obese women than in obese men before and during weight loss, but th e topography of fat tissue influences serum leptin concentrations. Ser um leptin concentrations do not predict the response to weight reducti on.