Table 1 Study characteristics of the included studies
Author, year | Study design, follow-up | Sample size Gender | Age (yr) BMI (kg/m2) LBM (kg) | Surgery type | Intervention | Pre-surgery protein intake (g/day) | Actual protein intake (g/day) | Compliance | Protein intake analyzed | Outcomes analyzed | |
|---|---|---|---|---|---|---|---|---|---|---|---|
CON | PRO | ||||||||||
Clements et al., 2011 [24] | Unblinded randomized control pilot study, 8 weeks | 30 M (n = 1) F (n = 29) | 46.0 ± 7.5 43.6 ± 4.2 54.0 ± 8.1 | 47.9 ± 9.6 42.9 ± 4.1 52.4 ± 6.9 | RYGB (n = 30) | CON: usual care, no use of protein supplements PRO: oral supplement containing 24 g leucine metabolite, glutamine and arginine twice daily for 8 weeks | NA | NA | NA | Log sheets | TBW, BMI Body composition using DXA (BFM, LBM) RMR |
Günes et al., 2019 [25] | Randomized controlled trial, 6 months | 60 M (n = 9) F (n = 51) | 43.5 ± 8.4 45.9 ± 6.5 61.7 ± 13.3 | 40.3 ± 11.4 46.2 ± 5.0 47.5 ± 13.5 | SG (n = 60) | CON: standard diet for 1 month, no use of protein supplements PRO: standard diet + 1,2 g/kg IBW/day protein (±80 g) whey powder for 1 month | NA | CON: NA PRO: 51 | 38%a | NA | TBW, BMI Body composition using BIA (BFM, LBM) |
Oppert et al., 2018 [26] | Randomized controlled trial, 6 months | 53 F (n = 53) | 43.9 ± 10,7 43.6 ± 6.2 55.6 ± 8.4 | 42.5 ± 8.7 43.3 ± 6.0 55.9 ± 6.1 | RYGB (n = 53) | CON: usual care with general dietary and physical activity counselling PRO: oral supplement containing whey-protein-enriched powder (24 g) twice daily for 6 months | CON: 80 PRO: 82 | CON: 60 PRO: 82 | 55% | Dietary history method. Return of empty cans of protein powder | TBW, BMI Body composition using DXA (BFM, LBM) |
Schiavo et al., 2017 [27] | Randomized comparative study, 12 months | 60 M (n = 60) | 41.0 ± 6.2 40.7 ± 5.3 75.0 ± 11.9 | 43.0 ± 5.5 42.1 ± 6.2 76.3 ± 7.0 | SG (n = 60) | NPD (normal protein diet): 1.0 g/kg IBW/day protein (23.3%), 15% fat and 61.7% carbohydrates for 12 months PED (protein-enriched diet): 2.0 g/kg ideal IBW/day protein (±160 g)(47.7%), 15% fat and 37.7% carbohydrates for 12 months | NA | CON: 67 PRO: 143 | Very high | Questionnaires, 3 day dietary record, 72 h-recall | TBW, BMI Body composition using BIA (BFM, LBM) RMR |
Schollenberger et al., 2016 [28] | Randomized controlled double-blind pilot study, 6 months | 20 M (n = 3) F (n = 17) | 47.0 ± 11.9 49.0 ± 5.1 68.9 ± 13.4 | 43.4 ± 13.3 52.0 ± 7.6 65.2 ± 14.2 | RYGB (n = 5) SG (n = 15) | CON: pure maltodextrin powder, 15 g/day first month, 30–35 g/day second-sixth month PRO: milk protein powder, 15 g/day first month, 30–35 g/day second-sixth month | CON: 93 PRO: 97 | CON: 53 PRO: 67 | 86% | 4 day dietary record, interviews | TBW, BMI Body composition using BIA (BFM, LBM) |