Objective: To evaluate interactions among leptin, adiponectin, resistin, ghrelin, and proinflammatory cytokines [tumor necrosis factor receptors (TNFRs), interleukin‐6 (IL‐6)] in nonmorbid and morbid obesity.

Research Methods and Procedures: We measured these hormones by immunoenzyme or radiometric assays in 117 nonmorbid and 57 morbidly obese patients, and in a subgroup of 34 morbidly obese patients before and 6 months after gastric bypass surgery. Insulin resistance by homeostasis model assessment, lipid profile, and anthropometrical measurements were also performed in all patients.

Results: Average plasma lipids in morbidly obese patients were elevated. IL‐6, leptin, adiponectin, and resistin were increased and ghrelin was decreased in morbidly obese compared with nonmorbidly obese subjects. After adjusting for age, gender, and BMI in nonmorbidly obese, adiponectin was positively associated with HDLc and gender and negatively with weight (β = −0.38, p < 0.001). Leptin and resistin correlated positively with soluble tumor necrosis factor receptor (sTNFR) 1 (β = 0.24, p = 0.01 and β = 0.28, p = 0.007). In the morbidly obese patients, resistin and ghrelin were positively associated with sTNFR2 (β = 0.39, p = 0.008 and β = 0.39, p = 0.01). In the surgically treated morbidly obese group, body weight decreased significantly and was best predicted by resistin concentrations before surgery (β = 0.45, p = 0.024). Plasma lipids, insulin resistance, leptin, sTNFR1, and IL‐6 decreased and adiponectin and ghrelin increased significantly. Insulin resistance improved after weight loss and correlated with high adiponectin levels.

Discussion: TNFα receptors were involved in the regulatory endocrine system of body adiposity independently of leptin and resistin axis in nonmorbidly obese patients. Our results suggest coordinated roles of adiponectin, resistin, and ghrelin in the modulation of the obesity proinflammatory environment and that resistin levels before surgery treatment are predictive of the extent of weight loss after bypass surgery.