A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults
Robert W. Morton et al.
British Journal of Sports Medicine · 2018
What the research tells us
Across 49 trials, supplementation added an average 0.30 kg of fat-free mass (95% CI 0.09–0.52) and 2.49 kg in one-repetition-maximum strength (0.64–4.33) to resistance-training gains. The estimated daily-intake breakpoint was 1.62 g/kg/day, with considerable uncertainty.
Scope & interpretation
The breakpoint analysis used 42 study arms and 723 participants: 95% CI 1.03–2.20 g/kg/day; the segmented model comparison did not reach conventional significance (p=.079). This is a study-level estimate, not an individual requirement, a safety ceiling or a proven optimum. Women and older adults had less evidence.
Study at a glance
- POPULATION & SAMPLE
- 49 randomized trials; 1,863 healthy adults, with a mixture of ages and training histories. Energy-restricted participants were excluded.
- EXPOSURE / INTERVENTION / SUBJECT
- Protein supplements plus resistance training versus training with placebo or no supplement; food-based and isolated-protein interventions were included.
- OUTCOMES
- Changes in fat-free mass, one-repetition-maximum strength and muscle size; these are not everyday fatigue or whole-body recovery measures.
- TIME FRAME
- Training lasted at least six weeks; publications spanned 1962–2016. Published online in 2017, in the 2018 journal issue.
Cited on this site
Editorial & review record
Record for v1.0 · Updated
Editorial responsibility: TAP Editorial Team
Editorial note
Under the editorial responsibility of the TAP Editorial Team, this publication used AI assistance for content organization and editing.
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How responsibilities and review are recorded ↗Scope of this reading note
PMC full text: eligibility, pooled results, breakpoint analysis and Figure 5, limitations and declarations. Individual trial data and all supplementary analyses were not independently reanalysed.
- Study funding
- Stuart M. Phillips acknowledged Canada Research Chairs, Canadian Institutes of Health Research and Natural Sciences and Engineering Research Council of Canada support.
- Competing interests
- Phillips disclosed grants, travel and presentation honoraria from the US National Dairy Council, which also supported trials included in the analysis.
Project support
Founded and supported by Resilio.
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