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. 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/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). 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.

Fat‐Free Mass and Skeletal Muscle Mass Five Years After Bariatric Surgery

“…Early observations by Forbes ( 24 ) point to a close linkage between body weight and FFM, such that some FFM loss is expected during body weight loss. Indeed, results from numerous studies have shown FFM losses of similar magnitude or greater than this study during rapid weight loss in the first 1–2 years after RYGB ( 7 , 25 , 26 , 27 , 28 , 29 , 30 ), SLEEVE ( 7 , 25 , 28 , 29 ), and BAND ( 7 , 26 , 27 , 31 , 32 , 33 ) procedures. The rate and amount of FFM lost during these initial post-operative years may vary by surgical procedure, extent of weight loss, and possibly assessment method.…”

“…Recent studies assessed FFM in bariatric surgery patients soon after weight loss compared with weight‐ and age‐matched controls and found the same or even greater FFM than expected within their BMI category . While these findings appear promising for bariatric surgery patients, it is important to note that most of the studies of FFM after surgically induced weight loss do not extend beyond the initial weight‐loss period (1‐2 years) .…”

Postprandial Nutrient Handling and Gastrointestinal Hormone Secretion After Roux-en-Y Gastric Bypass vs Sleeve Gastrectomy

“…This is supported by studies demonstrating higher FFM percentages after both RYGB and SG compared with unoperated controls, inconsistent with major FFM depletion after surgery. 50 Instead, the loss of FFM seems comparable to what is expected due to the weight loss itself. 51 The cross-sectional design of our study has the advantage that we were able to examine patients in the weightstable phase and to obtain matching for both pre-and postoperative BMI to minimize the confounding effect of differing postoperative weight losses.…”