Resting Energy Expenditure and Metabolic Adaptation in Adolescents at 12 Months After Bariatric Surgery

Background: Evidence suggests that metabolic adaptation occurs after bariatric surgery such that resting energy expenditure (REE) declines more than accounted for by body weight or body composition changes in adults. Little is known about REE and metabolic adaptation among adolescents after bariatric surgery. Objective: To examine changes in REE and metabolic adaptation among adolescents at 12 months (12M) after bariatric surgery. Setting: Pediatric hospital, Canada. Methods: Adolescents undergoing Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) were followed. Bioelectrical impedance analysis and indirect calorimetry were completed to measure body composition and REE, respectively. Predicted REE was calculated using the Mifflin equation before and after bariatric surgery and a predictive equation using preoperative data. Results: Among 20 patients (15 girls), the mean age and body mass index at surgery were 17.2 +/- 0.8 years and 48.7 +/- 7.4 kg/m(2), respectively. REE had decreased by 548.3 kcal/d at 12M postoperatively (P < 0.001). Metabolic adaptation, determined by two procedures, was negative and significantly different from baseline (P < 0.05). When stratified by surgery type, REE change at 12M was not significantly different (RYGB, 2494.0 +/- 260.9 kcal/d, n = 11; SG, -614.6 +/- 344.4 kcal/d, n = 9; P = 0.384). Among 13 patients with REE data at 6 and 12M, no statistically significant difference was found (P = 0.368). Conclusions: Predicted and measured REE was 19% and 25% lower at 12M, respectively, irrespective of bariatric surgery type. Metabolic adaptation might predispose adolescents to weight regain after bariatric surgery and warrants careful nutritional management and counseling.