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Table 1 Study characteristics of the included studies

From: The effect of additional protein on lean body mass preservation in post-bariatric surgery patients: a systematic review

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)
  1. Values are expressed as mean ± SD
  2. List of abbreviations: CON control group, PRO protein group, RGYB Roux-en-Y gastric bypass, SG sleeve gastrectomy, IBW ideal body weight, NA not assessed, TBW total body weight, BMI body mass index, BFM body fat mass, LBM lean body mass, RMR resting metabolic rate, DXA dual-energy X-ray absorptiometry, BIA bioelectrical impedance analysis
  3. a indicates the percentage of patients adhering to the guideline regarding protein intake (≥60 g/day)