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.