Body Composition, Basal Metabolic Rate and Leptin in Long-Term Weight Regain After Roux-en-Y Gastric Bypass Are Similar to Pre-surgical Obesity.

Purpose: The purpose of this study is to evaluate the relationship between body composition, basal metabolic rate (BMR), and serum concentrations of leptin with long-term weight regain after Roux-en-Y gastric bypass (RYGB) and compare it with obesity before surgery.

Materials And Methods: Prospective longitudinal analytical study. Three groups were formed: individuals 60 months post RYGB, with weight regain (G1) and without it (G2), and individuals with obesity who had not undergone bariatric surgery (G3). Body fat (BF), body fat mass (BFM), visceral fat (VF), fat-free mass (FFM), skeletal muscle mass (SMM), and BMR were assessed by octapolar and multi-frequency electrical bioimpedance. Fasting serum concentrations of leptin were measured.

Results: Seventy-two individuals were included, 24 in each group. Higher means of BF, BFM, VF, and leptin levels were observed in G1, when compared to G2 (BF: 47.5 ± 5.6 vs. 32.0 ± 8.0, p < 0.05; FBM: 47.8 ± 11.6 vs. 23.9 ± 7.0, p < 0.05; VF: 156.8 ± 30.2 vs. 96.1 ± 23.8, p < 0.05; leptin: 45,251.2 pg/mL ± 20,071.8 vs. 11,525.7 pg/mL ± 9177.5, p < 0.000). G1 and G2 did not differ in FFM, SMM, and BMR. G1 and G3 were similar according to BF, FFM, BMR, and leptin levels. Body composition, but not leptin, was correlated with %weight regain in G1 (FBM: r = 0.666, p < 0.000; BF: r = 0.428, p = 0.037; VF: r = 0.544, p = 0.006).

Conclusion: Long-term weight regain after RYGB is similar to pre-surgical obesity in body composition, BMR, and leptin concentrations, indicating relapse of metabolic and hormonal impairments associated with excessive body fat.