Weight Loss Increases Soluble Leptin Receptor Levels and the Soluble Receptor Bound Fraction of Leptin

Abstract

Abstract Objective: Soluble leptin receptor (sOB‐R) represents the main binding site for leptin in human blood. The aim of this study was to investigate the relationship between leptin and soluble leptin receptor and the bound/free ratio after pronounced weight reduction. Research Methods and Procedures: A total of 18 morbidly obese women participated in this prospective study. Subjects were examined for fat mass, leptin, and sOB‐R concentrations before and 1 year after Swedish adjustable gastric banding. Results: Anthropomorphic measures displayed a significant reduction of body mass index [(42.9 ± 5.6 to 32.9 ± 6.0 kg/m 2 (mean ± SD)]. Fat mass decreased from 56.3 ± 9.0 to 33.9 ± 12.5 kg. Plasma leptin concentration decreased from 44.6 ± 18.0 to 20.0 ± 13.1 ng/mL ( p < 0.001), whereas the sOB‐R levels increased from 11.1 ± 3.6 to 16.6 ± 6.0 U/mL after weight‐reducing surgery. Thus, the sOB‐R bound fraction of leptin increased from 7% to 33%. Discussion: This work demonstrates a relationship between weight loss, leptin, and sOB‐R concentrations in vivo. During weight loss, leptin levels decreased, whereas sOB‐R levels and the receptor bound fraction of leptin increased. Thus, sOB‐R may negatively regulate free leptin.