Body Composition, Serum Sclerostin and Physical Function After Bariatric Surgery: Performance of Dual-Energy X-ray Absorptiometry and Multifrequency Bioelectrical Impedance Analysis.

Introduction: The aim of this study was to determine the effects of bariatric surgery and weight loss on body composition, serum sclerostin and physical performance.

Methods: Seventy-three consecutive patients (36 non-surgical controls and 37 who underwent bariatric surgery) were evaluated by means of laboratory tests, multifrequency bioelectrical impedance analysis (BIA), total-body dual-energy X-ray absorptiometry (DXA), gait speed and handgrip strength.

Results: The differences between non-surgical and surgical patients were as follows: body mass index (BMI) 42.9 ± 5.7 vs 34.8 ± 6.0 kg/m (p < 0.001); handgrip strength 31.3 ± 7.0 vs 27.1 ± 9.3 kg (p < 0.033); skeletal muscle mass index (SMI)-BIA 12.3 ± 1.2 vs 10.6 ± 1.2 kg/m; fat-free mass index (FFMI)-BIA 21.9 ± 1.9 vs 18.9 ± 2.1 k/m (p < 0.001 for all comparisons); Baumgartner-DXA 10.8 ± 1.5 vs 9.0 ± 1.4 kg/m (p < 0.001); fat mass BIA 55.4 ± 12.5 vs 36.8 ± 9.6; fat mass DXA 54.3 ± 12.38 vs 35.1 ± 7.5 kg (p < 0.001 for both comparisons) and serum sclerostin 30.9 ± 31.9 vs 26.9 ± 21.1 pmol/L (p = 0.516). Positive correlation was found between BIA and DXA: SMI × Baumgartner (r = 0.842; p < 0.001) and fat mass (r = 0.970; p < 0.001). Gait speed was relatively preserved in sleeve gastrectomy (SG) compared with Roux-en-Y gastric bypass (RYGB) (1.2 ± 0.3 and 0.9 ± 0.1 m/s; p = 0.038).

Conclusion: Bariatric surgery leads to lower values of lean and fat mass and of handgrip strength with no differences in serum sclerostin concentrations. There was a positive correlation between BIA and DXA for fat and lean mass parameters. Physical performance was better after SG than in RYGB.