Nutrition
B · Reasonable confidenceWhey and soy protein with strength training: effect on lean mass and strength
Subject: The Impact of Whey and Soy Protein Supplementation on Resistance Training in Young Adults: A Systematic Review and Meta-Analysis
What this means
Neither whey nor soy protein significantly changed lean body mass. Whey protein did improve bench press (mean difference 8.87) and squat (mean difference 9.60).
Davis BE, Young I, Giglotti JC, Yao J, Tou JC · 2026 · Journal of Dietary Supplements
What does this rating mean?
A solid systematic review with caveats, or consistent indications with a limited scope.
Findings
Both whey and soy protein enhanced lean body mass and strength compared to placebo, with minimal differences between them when total protein was adequate — counter-evidence to the 'whey is always superior' narrative.
Who this applies to
Healthy young adults aged 18 to 30 doing resistance training, trained or untrained.
Size of the research
12 studies with a total of 261 participants.
What to keep in mind
The total number of participants was limited. The authors call for larger, high-quality trials before firm conclusions can be drawn.
Practical conclusion for REZA
For vegetarian or vegan clients: soy protein works just as well as whey for muscle and strength, as long as total protein intake is adequate.
View method and source
Methodology
Meta-analysis
Population
Young adults; RCTs of whey or soy protein + RT
Intervention
Whey protein + RT vs soy protein + RT vs placebo + RT
Outcome measures
Lean body mass, muscle strength
Limitations
Limited head-to-head studies; heterogeneity; varying doses.
Original source
DOI: 10.1080/19390211.2025.2604679 · PMID: 41454445
View on PubMed →This information is general education about scientific research. It is not personal medical advice and does not replace diagnosis or treatment by a doctor or other healthcare professional. If you have symptoms, a medical condition or take medication, consult your GP or treating professional before changing your training or nutrition.