FitProven
Evidence Breakdown
Based on 3 studies
THE BIGGER QUESTION
Whether this one statement holds is settled above. What to actually do about it is a wider question, weighed across every claim that bears on it.
- What's the right way to train for muscle growth? — this claim is one of 5 weighed there
Evidence map
For & against, at a glance
Meta-Analysis
Pro
Morton RW et al. · 2018British Journal of Sports MedicineLarge meta-analysis of 49 studies (1863 participants) found that dietary protein supplementation significantly augmented resistance training-induced gains in muscle mass and strength. The analysis identified a breakpoint at 1.62 g/kg/day beyond which additional protein did not further contribute to resistance training-induced gains in fat-free mass.
0.90
Large meta-analysis of 49 studies (1863 participants) found that dietary protein supplementation significantly augmented resistance training-induced gains in muscle mass and strength. The analysis identified a breakpoint at 1.62 g/kg/day beyond which additional protein did not further contribute to resistance training-induced gains in fat-free mass.
Design Meta-Analysis (1.0) × quality 0.90 = impact 0.90
View sourceMeta-Analysis
Pro
Cermak NM et al. · 2012American Journal of Clinical NutritionMeta-analysis of 22 RCTs showed that protein supplementation during prolonged resistance-type exercise training augmented gains in fat-free mass (+0.69 kg, 95% CI 0.47-0.91) and 1-RM leg press strength compared to placebo. Effects were observed in both younger and older populations.
0.85
Meta-analysis of 22 RCTs showed that protein supplementation during prolonged resistance-type exercise training augmented gains in fat-free mass (+0.69 kg, 95% CI 0.47-0.91) and 1-RM leg press strength compared to placebo. Effects were observed in both younger and older populations.
Design Meta-Analysis (1.0) × quality 0.85 = impact 0.85
View sourceCrossover Trial
Neutral
Bandegan A et al. · 2017Journal of NutritionA single primary indicator amino acid oxidation (IAAO) study — not a meta-analysis — in **eight** young male bodybuilders, run across 42 experiments at test intakes of 0.1–3.5 g/kg/day. The Estimated Average Requirement was 1.7 g/kg/day and the upper 95% CI (the RDA-equivalent) 2.2 g/kg/day, which the authors note "exceed the current recommendations of the Institute of Medicine by ~2.6-fold." Important scope limit that the title states outright: participants were "studied at rest **on a nontraining day**", so this is not a measurement taken during intensive training. It is a short-term oxidation surrogate in eight men, not a muscle or performance outcome.
0.26
A single primary indicator amino acid oxidation (IAAO) study — not a meta-analysis — in **eight** young male bodybuilders, run across 42 experiments at test intakes of 0.1–3.5 g/kg/day. The Estimated Average Requirement was 1.7 g/kg/day and the upper 95% CI (the RDA-equivalent) 2.2 g/kg/day, which the authors note "exceed the current recommendations of the Institute of Medicine by ~2.6-fold." Important scope limit that the title states outright: participants were "studied at rest **on a nontraining day**", so this is not a measurement taken during intensive training. It is a short-term oxidation surrogate in eight men, not a muscle or performance outcome.
Design Crossover Trial (0.75) × quality 0.35 = impact 0.26
View sourceMeta-Analysis
Pro
Morton RW et al. · 2018British Journal of Sports MedicineLarge meta-analysis of 49 studies (1863 participants) found that dietary protein supplementation significantly augmented resistance training-induced gains in muscle mass and strength. The analysis identified a breakpoint at 1.62 g/kg/day beyond which additional protein did not further contribute to resistance training-induced gains in fat-free mass.
0.90
Large meta-analysis of 49 studies (1863 participants) found that dietary protein supplementation significantly augmented resistance training-induced gains in muscle mass and strength. The analysis identified a breakpoint at 1.62 g/kg/day beyond which additional protein did not further contribute to resistance training-induced gains in fat-free mass.
Design Meta-Analysis (1.0) × quality 0.90 = impact 0.90
View sourceMeta-Analysis
Pro
Cermak NM et al. · 2012American Journal of Clinical NutritionMeta-analysis of 22 RCTs showed that protein supplementation during prolonged resistance-type exercise training augmented gains in fat-free mass (+0.69 kg, 95% CI 0.47-0.91) and 1-RM leg press strength compared to placebo. Effects were observed in both younger and older populations.
0.85
Meta-analysis of 22 RCTs showed that protein supplementation during prolonged resistance-type exercise training augmented gains in fat-free mass (+0.69 kg, 95% CI 0.47-0.91) and 1-RM leg press strength compared to placebo. Effects were observed in both younger and older populations.
Design Meta-Analysis (1.0) × quality 0.85 = impact 0.85
View sourceCrossover Trial
Neutral
Bandegan A et al. · 2017Journal of NutritionA single primary indicator amino acid oxidation (IAAO) study — not a meta-analysis — in **eight** young male bodybuilders, run across 42 experiments at test intakes of 0.1–3.5 g/kg/day. The Estimated Average Requirement was 1.7 g/kg/day and the upper 95% CI (the RDA-equivalent) 2.2 g/kg/day, which the authors note "exceed the current recommendations of the Institute of Medicine by ~2.6-fold." Important scope limit that the title states outright: participants were "studied at rest **on a nontraining day**", so this is not a measurement taken during intensive training. It is a short-term oxidation surrogate in eight men, not a muscle or performance outcome.
0.26
A single primary indicator amino acid oxidation (IAAO) study — not a meta-analysis — in **eight** young male bodybuilders, run across 42 experiments at test intakes of 0.1–3.5 g/kg/day. The Estimated Average Requirement was 1.7 g/kg/day and the upper 95% CI (the RDA-equivalent) 2.2 g/kg/day, which the authors note "exceed the current recommendations of the Institute of Medicine by ~2.6-fold." Important scope limit that the title states outright: participants were "studied at rest **on a nontraining day**", so this is not a measurement taken during intensive training. It is a short-term oxidation surrogate in eight men, not a muscle or performance outcome.
Design Crossover Trial (0.75) × quality 0.35 = impact 0.26
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Evidence
PRO (2)
PRO Meta-Analysisn=1863INDUSTRY0.90 Morton RW, Murphy KT et al. (2018)
Protein supplementation augmented resistance-training gains in fat-free mass and strength; the benefit plateaued at a breakpoint of 1.62 g/kg/day
Large meta-analysis of 49 studies (1863 participants) found that dietary protein supplementation significantly augmented resistance training-induced gains in muscle mass and strength. The analysis identified a breakpoint at 1.62 g/kg/day beyond which additional protein did not further contribute to resistance training-induced gains in fat-free mass.
Weighted 0.90 — 49 RCTs and 1,863 participants — large, well-powered and methodologically strong (meta-regression with a fitted breakpoint). Discounted only because the senior author has funding and honoraria ties to the US National Dairy Council, an agency that supported some of the pooled trials, on a positive result.
Funding: Author support from Canada Research Chairs, CIHR and NSERC; senior author declares grants, travel expenses and honoraria from the US National Dairy Council, which funded trials included in the analysis
British Journal of Sports Medicine
PRO Meta-Analysisn=6800.85 Cermak NM, Res PT et al. (2012)
Protein supplementation added +0.69 kg fat-free mass (95% CI 0.47-0.91) and +13.5 kg 1-RM leg press vs placebo across 22 RCTs
Meta-analysis of 22 RCTs showed that protein supplementation during prolonged resistance-type exercise training augmented gains in fat-free mass (+0.69 kg, 95% CI 0.47-0.91) and 1-RM leg press strength compared to placebo. Effects were observed in both younger and older populations.
Weighted 0.85 — 22 RCTs pooling 680 participants across young and older adults, publicly funded with an explicit no-COI declaration. Solid and well-conducted; held below the top band because the pooled sample is only moderate, the component trials vary widely in protein dose, timing and training programme, and effect sizes in the untrained are inflated relative to trained lifters.
Funding: Canadian Institutes of Health Research (postdoctoral fellowship); authors declared no conflict of interest
American Journal of Clinical Nutrition
NEUTRAL (1)
NEUTRAL Crossover Trialn=80.35 Bandegan A, Courtney-Martin G et al. (2017)
Indicator amino acid oxidation gave a mean protein requirement of 1.7 g/kg/day and an upper 95% CI of 2.2 g/kg/day on a non-training day — about 2.6-fold the Institute of Medicine RDA
A single primary indicator amino acid oxidation (IAAO) study — not a meta-analysis — in eight young male bodybuilders, run across 42 experiments at test intakes of 0.1–3.5 g/kg/day. The Estimated Average Requirement was 1.7 g/kg/day and the upper 95% CI (the RDA-equivalent) 2.2 g/kg/day, which the authors note "exceed the current recommendations of the Institute of Medicine by ~2.6-fold." Important scope limit that the title states outright: participants were "studied at rest on a nontraining day", so this is not a measurement taken during intensive training. It is a short-term oxidation surrogate in eight men, not a muscle or performance outcome.
Weighted 0.35 — n=8 male bodybuilders (42 IAAO experiments across intakes of 0.1-3.5 g/kg/day). A tightly controlled stable-isotope study from an established lab, but tiny, male-only, single-lab, measured on a non-training day only, and it uses a short-term oxidation surrogate rather than any muscle or performance outcome — serious indirectness for a claim about training adaptation. Authors declared no conflicts of interest; no funding statement could be verified, so that field is omitted. NOTE: study_type is recorded as meta_analysis but this is a primary IAAO study — flagged, not changed.
Journal of Nutrition