Effects of Roux-en-Y Gastric Bypass on Resting Energy Expenditure in Women

Background Bariatric surgery is the gold standard treatment for morbid obesity, but little is known about its effects on resting energy expenditure. Method Twenty-one women underwent anthropometric and resting energy expenditure (REE) measurements before and 3 months after bariatric surgery using the Roux-en-Y gastric bypass (RYGBP) technique developed by Capella. Results The patients experienced a significant reduction in body weight, body mass index, waist circumference, and waist-to-hip ratio (WHR). The cardiopulmonary variables oxygen uptake, carbon dioxide output, non-protein respiratory quotient, and heart rate all decreased, whereas oxygen pulse did not change significantly. Absolute REE showed a significant reduction 3 months postoperatively (2006.7 +/- 376.4 kcal/day to 1763.3 +/- 310.5 kcal/day), but no significant difference was found compared with REE relative to body weight (0.71 +/- 0.15 kcal (-1)h(-1) to 0.75 +/- 0.12 kcal kg (-1)h(-1) or as percent of Harris-Benedict predicted REE (106.2 +/- 21.0% to 103.3 +/- 15.1%). Conclusion In this study, bariatric surgery using the RYGBP technique (Capella) led to a significant decrease of body weight that decreased resting energy expenditure proportional to this weight loss, and to an increase in the utilization of fat as an energy substrate. It can be concluded that after 3 months, the Roux-en-Y gastric bypass surgery may provide significant metabolic benefits to morbidly obese women.