Effects of a weight-reduction program with orlistat on serum leptin levels in obese women: A 12-week, randomized, placebo-controlled study

Background: Leptin, which has been identified as an antiobesity hormone, regulates body weight by controlling food intake and energy expenditure via the hypothalamic-pituitary-gonadal axis. It appears that leptin may be an important factor in obesity management. Orlistat, a pancreatic lipase inhibitor, could reduce fat absorption and promote weight loss due to leptin metabolism.Objective: The purpose of this study was to investigate the effects of orlistat therapy on serum leptin levels.Methods: Obese women (body mass index BMI], 30 kg/m²) aged 18 to 50 years were randomly assigned to receive 12 weeks of oral treatment with diet-orlistat (120 mg TID) (DO group) or diet-placebo (DP group). During the treatment period, patients were asked to eat a balanced diet of -1200 to 1600 kcal/d. Body composition was determined by bioelectrical impedance. Serum leptin levels were measured using radioimmunoassay at baseline and at study end.Results: A total of 24 patients entered the study; 14 patients (mean SE] BMI, 37.7 1.1] kg/m²) received orlistat and 10 patients (mean SE] BMI, 39.4 1.3] kg/m²) received placebo. Compared with baseline, mean percentages of loss of body weight and fat mass after 12 weeks of treatment were significant in the DO group (9.1% and 14.8%, respectively; both P = 0.001) and in the DP group (9.5% and 17.6%; both P = 0.005). The between-group differences were not statistically significant. Mean (SE) serum leptin levels also decreased significantly after treatment in the DO group (16.2 1.2] vs 9.0 1.0] ng/mL; P = 0.001) and in the DP group (19.3 2.1] vs 9.7 1.4] ng/mL; P = 0.005). The between-group difference was not statistically significant.Conclusions: In this study of obese women, orlistat treatment was associated with a similar decrease in body weight, fat mass, and serum leptin levels as placebo over a 12-week period. In this regard, short-term orlistat therapy may not provide an additional effect on serum leptin levels, and reduction in leptin levels were closely related to the decrease in fat mass.