Body fat mass and distribution as predictors of metabolic outcome and weight loss after Roux-en-Y gastric bypass

Background: Bariatric surgery such as Roux-en-Y gastric bypass (RYGB) remains the most effective treatment of obesity and associated co-morbidities. Body fat distribution associates with metabolic function. Objective: To investigate if preoperative body fat mass and distribution measured by dual-energy x-ray absorptiometry (DXA) predict weight loss and metabolic outcome after RYGB, and to compare predictive value of DXA with simple anthropometric measures. Setting: Four Swedish hospitals within the Stockholm area. Methods: Two hundred fifteen women scheduled for RYGB were included. Evaluations before and 2 years after RYGB included determination of insulin sensitivity by the homeostatic model assessment of insulin resistance, blood pressure, plasma lipids, and anthropometric measures, such as waist-to-hip-ratio and fat percentage estimated by formula. Body fat mass and distribution were determined by DXA. Results: Follow-up rate was 77.2% (n = 166). All clinical, anthropometric, and DXA measures were improved/reduced postsurgery (all P < .0001). Android/gynoid fat mass ratio and waist-to hip-ratio predicted improved homeostatic model assessment of insulin resistance (P = .0028 and .0014), independently of body mass index and age. Body fat percentage, measured by DXA or estimated by formula, predicted percent weight loss (P < .0001 and .0083). Body mass index predicted percent weight loss and percent excess body mass index lost (P = .0022 and < .0001). DXA and anthropometric measures performed equally as predictors, except for DXA measured fat percentage that was slightly better than formula estimated. Conclusion: DXA provided predictive values similar to those by basic anthropometric measures, suggesting a limited additional value of preoperative DXA to predict metabolic improvement and weight loss after RYGB in women. (C) 2018 American Society for Metabolic and Bariatric Surgery. All rights reserved.