Changes in Body Composition with Weight Loss: Obese Subjects Randomized to Surgical and Medical Programs

OBJECTIVE: To assess changes in body composition with weight loss in obese subjects randomized to a laparoscopic adjustable gastric band surgical program or a medical program using a very-low-energy diet and orlistat. RESEARCH METHODS AND PROCEDURES: Using body composition measurements by DXA, neutron activation for total body nitrogen, and whole body gamma counting for total body potassium, we studied changes in fat mass, fat distribution, fat-free mass, total bone mineral content, total body protein, and body cell mass at 6 (n = 61 paired) and 24 months (n = 53 paired) after randomization. RESULTS: At 24 months, the surgical group had lost significantly more weight (surgical, 20.3 plus or minus 6.5 kg; medical, 5.9 plus or minus 8.0 kg). There was favorable fat-free mass to fat mass loss ratios for both groups (surgical, 1:5.5; medical, 1:5.9). Changes in total body nitrogen or potassium were favorable in each group. A small reduction in mean bone mineral content occurred throughout the study but was not associated with extent of weight loss or treatment group. At 6 months, weight loss for both groups was similar (surgical, 14.1 plus or minus 4.5 kg; medical, 13.3 plus or minus 7.3 kg). The medical program subjects lost less fat-free mass and skeletal muscle and had increased total body protein. The proportion of body fat to limb fat remained remarkably constant throughout the study. DISCUSSION: Weight loss programs used in this study induced fat loss without significant deleterious effects on the components of fat-free mass.