RELATIONSHIP BETWEEN ENERGY-EXPENDITURE AND VISCERAL FAT ACCUMULATIONIN OBESE WOMEN SUBMITTED TO ADJUSTABLE SILICONE GASTRIC BANDING (ASGB)

OBJECTIVE: To analyze the relationship between visceral fat accumulati on and resting energy expenditure in obese women and to evaluate the e ffects of a severe weight loss both on energy expenditure and on fat d istribution. DESIGN: Twelve premenopausal women, aged 19-50 years, und ergoing adjustable silicone gastric banding (ASGB) for morbid obesity participated at the study. The patients were evaluated twice. The base line evaluation was performed immediately before surgery. After surger y, a diet specifically developed for patients submitted to gastric res triction (2.5 MJ/day) was given to the patients. The second evaluation was performed 6 months after surgery. MEASUREMENTS: Resting metabolic rate (RMR) was determined by indirect calorimetry. Total fat area (TF A), visceral fat area (VFA) and subcutaneous fat area (SFA) were measu red by abdominal computed tomography. Fat mass (FM) and fat free mass (FFM) were derived by bioelectrical impedance analysis. RESULTS: At ba seline, RMR was positively related to VFA (r = 0.60, P < 0.05). ASGB i nduced a highly significant weight loss of 24.4 +/- 9.0 kg. This weigh t reduction was mainly due to a loss of FM (68.5 +/- 10.8 vs 48.5 +/- 9.2 kg, P < 0.001), whereas FFM was only slightly reduced (52.6 +/- 4. 0 vs 47.9 +/- 4.6 kg, P < 0.05). The BMI reduction was positively rela ted to the baseline BMI and FM values (r = 0.61, P < 0.05 and r = 0.55 , P < 0.05, respectively). There was no significant correlation betwee n the BMI reduction and the baseline variables of fat distribution, no r between the BMI reduction and the basal RMR. Weight loss was accompa nied by modifications of fat distribution. In particular, the reductio n of VFA after surgery was strictly related to the VFA values at basel ine (r = 0.91, P < 0.001). Weight loss induced a significant reduction of RMR (7.96 < 1.77 vs 6.57 +/- 6.90 MJ/day; P < 0.01). The reduction of the RMR observed with weight loss was significantly related to the FFM loss (r = 0.63, P < 0.05), whereas no correlations were found bet ween the changes of RMR and the FM loss. Regarding to fat distribution , the reduction of the RMR was significantly related to the visceral f at loss (r = 0.57, P < 0.05), but not to the modifications of total or subcutaneous fat area. The independent contribution of the modificati ons of FFM, FM, and visceral fat to the changes of RMR was analyzed by multiple regression analysis. In this model, both FFM and visceral fa t changes resulted independently related to the RMR. CONCLUSIONS: (1) visceral fat accumulation was a significant predictor of RMR in the ve ry obese woman; (2) visceral obese women lost more visceral fat than s ubcutaneous ones; (3) the reduction of the RMR observed during weight loss could partly be explained by a reduction of visceral fat mass.