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.

objectiveSleeve 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.

methodsA 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.

resultsOne 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.

conclusionThere 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.