Meta-analysisindependent cross-checkabstract checked★ key study I-FAST-121 standard review

Protein and muscle in healthy adults

Systematic review and meta-analysis of protein intake to support muscle mass and function in healthy adults.

Overview

Nunes EA et al.. J Cachexia Sarcopenia Muscle 2022 · PMID 35187864 · DOI 10.1002/jcsm.12922

Eating more protein each day slightly increased muscle mass in people doing strength training.

Does the study support the specific claim? No · Methodological quality: moderate

Study explained simply

What did the researchers want to find out?: Pool RCTs on protein and muscle.
How was the study done?: Meta-analysis of 74 RCTs.
How many people, animals or samples were studied?: Healthy adults.
What was actually found?: Small LBM gains.
How large was the observed effect?: SMD 0.22 (0.14-0.30).
What do the results mean in everyday life?: Regular adequate protein helps keep muscle, especially when older.
What are the study's limitations?: Mostly in exercisers.
What does it say about Elawady's specific claim?: Indirectly contradicts alternate-day protein.
Do the results apply to Germany and Europe?: Applies; same physiology.
What can explicitly not be concluded from this study?: Effect of protein-free days.

Authors: Nunes EA et al.
Journal: J Cachexia Sarcopenia Muscle
Year: 2022
Identifier: PMID 35187864 DOI 10.1002/jcsm.12922
Verification: verified – PubMed efetch 2026-10-26; Crossref update-to/updated-by check
Retracted: no
Corrections: none
Extent checked: abstract only
Conflicts of interest and funding: One author reports dairy and beef industry honoraria and a patent (stated).

Does increasing daily protein intake increase lean body mass, strength and function in healthy adults?

Study design: Meta-analysis – Systematic review, three-level meta-analysis and meta-regression of RCTs
Population: Healthy non-obese adults
Country: International
Period: not stated in abstract
Sample size: 74 RCTs
Inclusion and exclusion criteria: not stated in abstract

Results: LBM gain with more protein during resistance exercise SMD 0.22 (95% CI 0.14-0.30; 62 studies; moderate evidence); significant in >=65-year-olds at 1.2-1.59 g/kg/day and <65 at >=1.6 g/kg/day with resistance exercise. Lower-body strength SMD printed as 0.40 with CI 0.09-0.35 (internally inconsistent).
Absolute risks: not reported
Authors' conclusion: Increasing daily protein results in small additional LBM and lower-body strength gains in healthy adults doing resistance training.

LBM effect small but consistent; strength CI misprinted (stats/I-FAST-121_nunes_protein.py).

Supports that adequate daily protein supports muscle mass, especially in older adults; indirect for alternate-day intake.

Universal biology; applies in Europe and Egypt.

Indirect contradicting evidence for reducing protein to alternate days.

Multidimensional assessment
Multidimensional assessment
Authenticity of the source	verified
Methodological quality	moderate
Risk of bias	some concerns
Precision of results	moderate
Directness	indirect
Reproducibility	replicated
Consistency with the overall evidence	consistent
Regional transferability	high
Adequacy of the interpretation (by the archive)	essentially correct but incomplete