The Effect of Protein Consumption on Fat-Free Mass, Fat Mass, and Weight Loss 1 Year After Sleeve Gastrectomy and Roux-en-Y Gastric Bypass

Objective Sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) both limit protein and calorie intake and result in loss of fat-free mass (FFM), fat mass (FM), and weight. This study examined protein consumption and body composition changes after bariatric surgery. Methods A prospective study of patients undergoing SG and RYGB between January 1 and December 31, 2016, with 1-year follow-up. Dietary, body composition, and physical activity data were collected at 3, 6, and 12 months post-operatively by bioelectric impedance and food records. Clinical laboratory data were obtained pre- and post-surgery. Results One hundred and five patients (62 [59%] SG and 43 [41%] RYGB) were included in this study. Mean age was 31.8 ± 7.22 years. TWL% after 1 year in SG was 27.11% ( p < 0.001) and that in RYGB was 30.41% ( p < 0.0001). Reported protein consumptions after RYGB increased from 41.59 ± 22.86 g/day at 3 months ( p = 0.004) to 57.90 ± 19.24 g/day at 12 months compared to 52.36 ± 25.04 g and 53.54 ± 29.75 g in SG. Similarly, energy intake after RYGB at 3 and 12 months increased from 895.9 ± 422.61 to 1188.15 ± 463.86 kcal/day compared to 1007.67 ± 422.62 to 1068 ± 575.89 kcal/day after SG ( p = 0.009). There was a significant loss of fat-free mass and muscle mass in SG patients at 3 and 12 months from 61.58 ± 3.61 kg and 58.47 ± 3.09 kg to 54.18 ± 11.05 ( p < 0.001) and 51.55 ± 10.62 ( p = 0.004) but not in RYGB patients. Physical activity levels were similar in SG and RYGB patients. Conclusion There was a significant preservation of muscle mass after RYGB. Protein intake in majority of the patients was below 60 g/day during the first year after SG and RYGB. Graphical Abstract