title: Fat-free mass is not lower 24 months postbariatric surgery than nonoperated matched controls.
abstract: OBJECTIVE
  Concerns about an excessive loss of fat-free mass (FFM) after bariatric surgery prompted this comparison of operated versus matched nonoperated controls regarding FFM.
  
  
  METHODS
  University Hospital and University Research Unit in an urban medical center.
  
  
  METHODS
  Body composition with bioelectric impedance (Tanita 310, Tanita Corp, Arlington Heights, IL) was measured approximately 2 years after bariatric surgery in weight stable patients and nonoperated weight stable controls matched for body mass index (BMI), gender, and age. t tests provided comparisons. Analysis of variance was used to compare FFM changes for 4 procedures. Levene's test evaluated variance.
  
  
  RESULTS
  Patients (n = 252; 24.7±15 mo after surgery) and nonoperated controls (n = 252) were matched for gender (71.8% female), age (44.5±11.0 yr), and BMI (32.8±7.0 kg/m2). Patients had different surgical procedures: 107 gastric bypasses (RYGBs), 62 biliopancreatic diversions with duodenal switch (BPD/DSs), 40 adjustable gastric bands (AGBs), and 43 sleeve gastrectomies (LSGs). FFM percentage was significantly higher in the operated patients than controls, 66% versus 62%, P<.0001. For 3 procedures, the FFM was significantly higher; however, AGBs changed only 7.3 BMI units and FFM was not significantly different from their matched controls, 59.8% versus 58.2%. Across surgical groups, FFM percentage differed, P<.0001 (RYGB 66.5±9.2%, BPD/DS 74.0±9.3%, AGB 59.8±7.0%, LSG 59.6±9.3%). Variance was not different (P = .17).
  
  
  CONCLUSIONS
  Weight-reduced bariatric surgery patients have greater FFM compared with nonoperated matched controls. These findings support surgically assisted weight loss as a physiologic process and in general patients do not suffer from excessive FFM depletion after bariatric procedures.
authors.affiliation: Weill Cornell College of Medicine, Department of Surgery, New York, New York. Electronic address: gls2010@med.cornell.edu.
authors.forename: Gladys Witt
authors.initials: GW
authors.lastname: Strain
authors.affiliation: Weill Cornell College of Medicine, Department of Surgery, New York, New York.
authors.forename: Faith
authors.initials: F
authors.lastname: Ebel
authors.affiliation: Weill Cornell College of Medicine, Department of Surgery, New York, New York.
authors.forename: Jamie
authors.initials: J
authors.lastname: Honohan
authors.affiliation: Hopital du Sacre Coeur, Department of Surgery, Montreal, Canada.
authors.forename: Michel
authors.initials: M
authors.lastname: Gagner
authors.affiliation: Weill Cornell College of Medicine, Department of Surgery, New York, New York.
authors.forename: Gregory F
authors.initials: GF
authors.lastname: Dakin
authors.affiliation: Weill Cornell College of Medicine, Department of Surgery, New York, New York.
authors.forename: Alfons
authors.initials: A
authors.lastname: Pomp
authors.affiliation: Columbia University, Obesity Research Center, New York, New York.
authors.forename: Dympna
authors.initials: D
authors.lastname: Gallagher
mesh_terms: D000273:Adipose Tissue / Q000473:pathology; D000328:Adult; D050110:Bariatric Surgery / Q000379:methods*; D001823:Body Composition; D015992:Body Mass Index; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000473:pathology / Q000601:surgery*; D011182:Postoperative Care; D015431:Weight Loss / Q000502:physiology
keywords: Bariatric surgery; Body composition after bariatric surgery; Composition of weight loss; Fat-free mass; Obesity