title: Preserved Fat-Free Mass after Gastric Bypass and Duodenal Switch.
abstract: Concerns for the possibility of an excessive loss of fat-free mass (FFM) and resting metabolic rate (RMR) after bariatric surgery, such as Roux-en-Y gastric bypass (RYGB) and duodenal switch (BPD/DS), have been raised.
  
  
  
  This study aims to examine body composition and RMR in patients after RYGB and BPD/DS and in non-operated controls.
  
  
  
  Body composition and RMR were studied with Bod Pod and indirect calorimetry in weight-stable RYGB (n = 15) and BPD/DS patients (n = 12) and compared with non-operated controls (n = 17). All patients were 30-55 years old and weight stable with BMI 28-35 kg/m2.
  
  
  
  FFM% was 58% (RYGB), 61% (BPD/DS), and 58% (controls). Body composition did not differ after RYGB and BPD/DS compared to controls, despite 27 and 40% total body weight loss, respectively. No difference in RMR or RMR/FFM was observed (1539, 1617, and 1490 kcal/24 h; and 28.9, 28.4, and 28.8 kcal/24 h/kg).
  
  
  
  Weight-stable patients with BMI 28-35 kg/m2after RYGB and BPD/DS have a body composition and RMR similar to that of non-operated individuals within the same BMI interval.
authors.affiliation: Department of Surgical Sciences, Uppsala University, SE-751 85, Uppsala, Sweden. martin.skogar@akademiska.se.
authors.forename: Martin
authors.identifier: 0000-0002-6840-2749
authors.initials: M
authors.lastname: Skogar
authors.affiliation: Department of Public Health and Caring Sciences, Clinical Nutrition and Metabolism, Uppsala University, SE-751 85, Uppsala, Sweden.
authors.forename: Ulf
authors.initials: U
authors.lastname: Holmbäck
authors.affiliation: Department of Surgical Sciences, Uppsala University, SE-751 85, Uppsala, Sweden.
authors.forename: Jakob
authors.initials: J
authors.lastname: Hedberg
authors.affiliation: Department of Public Health and Caring Sciences, Clinical Nutrition and Metabolism, Uppsala University, SE-751 85, Uppsala, Sweden.
authors.forename: Ulf
authors.initials: U
authors.lastname: Risérus
authors.affiliation: Department of Surgical Sciences, Uppsala University, SE-751 85, Uppsala, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Sundbom
mesh_terms: D000328:Adult; D001481:Basal Metabolism / Q000502:physiology*; D001823:Body Composition / Q000502:physiology*; D016022:Case-Control Studies; D015390:Gastric Bypass / Q000706:statistics & numerical data*; D006801:Humans; D008875:Middle Aged; D009767:Obesity, Morbid / Q000453:epidemiology / Q000601:surgery
keywords: Air-displacement plethysmography; Bariatric surgery; Bod Pod; Body composition; Duodenal switch; Fat-free mass; Indirect calorimetry assessment; Obesity; Resting metabolic rate; Roux-en-Y gastric bypass