Fat-free mass is not lower 24 months postbariatric surgery than nonoperated matched controls.

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. Setting: 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/m(2)). 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). Conclusion: 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. (C) 2017 American Society for Metabolic and Bariatric Surgery. All rights reserved.