Body composition and energy expenditure in obese patients prior to and following biliopancreatic diversion for obesity.

Body composition and resting energy expenditure (REE) were assessed in 69 obese patients prior to and 1 year following biliopancreatic diversion (BPD). Fat-free mass (FFM) and body fat sizes were very similar to those of nonoperated subjects closely matched for body weight and FFM size. In the BPD subjects, the REE data were high, thus excluding a dilatation of non-energy-consuming extracellular spaces and suggesting an increase in the ratio between the organs and the less metabolically active muscle mass within the FFM.