Whey Protein and Increased Lean Mass

Research synthesisLow evidenceMixed effect size4 studies · 2 beneficial · 2 neutral · 0 harmful

Across 4 studies, 2 reported beneficial effects (large and moderate effect sizes) while 2 found neutral effects. The median study duration was 84 days, suggesting effects may require ~12 weeks. Evidence does not converge on a specific dose, but two studies used 24–45 g/day of whey protein. Populations studied include older adults and younger adults.

Caveats: Evidence base is small (4 studies) and results are mixed. The highest-quality meta-analysis (n=980) found no significant effect, while a smaller meta-analysis of co-supplementation with vitamin D found a large benefit. One RCT showed a significant increase in lean mass (p=0.009) but was coded as neutral, possibly due to multiple comparisons or adjusted analyses. Studies vary in population (older vs younger) and use different doses, limiting confidence in the overall effect.

Generated Jul 12, 2026

Doses used in studies

g single-dose: 24 (median 24, IQR 24–24) — 1 study
g/day: 45 (median 45, IQR 45–45) — 1 study

Time to effect

Median: 2.8 months · IQR 2.8 months–2.8 months · Range 2.8 months–2.8 months — Reported in 2 of 4 studies

4 of 4 papersPopulation:

Explore the Optimal Treatment Regimen Across Combinations of Variate Protein Sources and Exercise Modalities and Its Associated Factors in Older Adults: A Network Meta-Analysis and Meta-Regression of Randomized Controlled Trials.
- 2026-04-29
- Meta-Analysis · n = 980
- Nutrients 18(9)
- - Che-Li Lin
  - Shih-Wei Huang
  - Hung-Chou Chen
  - Mao-Hua Huang
  - Tsan-Hon Liou
  - Chun-De Liao
- PubMed: 42124009
- DOI: 10.3390/nu18091409
6 Insights on
- Increased Lean Mass
- High evidence
- Rigorous Journal
- Elderly
This paper determined the optimal regimen among the composites of variate protein sources ... (milk was among the 10 sources analyzed; network meta-analysis includes all sources and the conclusion singled out whey, implying milk did not show a significant large effect).
Effect
Neutral
Effect size
Small
Significant
No
Whey Protein Supplementation with or without Vitamin D on Sarcopenia-Related Measures: A Systematic Review and Meta-Analysis.
- 2023-07
- Meta-Analysis · n = 33
- Advances in nutrition (Bethesda, Md.) 14(4)
- - Nasrin Nasimi
  - Zahra Sohrabi
  - Everson A Nunes
  - Erfan Sadeghi
  - Sanaz Jamshidi
  - Zohreh Gholami
  - Marzieh Akbarzadeh
  - Shiva Faghih
  - Masoumeh Akhlaghi
  - Stuart M Phillips
- PubMed: 37196876
- DOI: 10.1016/j.advnut.2023.05.011
6 Insights on
- Increased Lean Mass
- High evidence
- Clinical
co-supplementation with vitamin D enhanced LM gains (SMD =0.993; 95% CI: 0.112, 1.874; n = 11)
Effect
Beneficial
Effect size
Large
Significant
Yes
Post-Exercise Whey Protein Supplementation: Effects on IGF-1, Strength, and Body Composition in Pre-Menopausal Women, a Randomised Controlled Trial.
- 2025-06-18
- RCT
- Nutrients 17(12)
- - Marc Murray
  - Lara Vlietstra
  - Alyssa M D Best
  - Stacy T Sims
  - James A Loehr
  - Nancy J Rehrer
- PubMed: 40573144
- DOI: 10.3390/nu17122033
6 Insights on
- Increased Lean Mass
- High evidence
- Rigorous Journal
- Adults
Total lean mass increased (0.84 ± 0.80 kg, 0.56 ± 1.4 kg, CON, PRO, resp., p = 0.009)
Effect
Neutral
Effect size
Small
Significant
No
Dose
24 g
Similar effects between animal-based and plant-based protein blend as complementary dietary protein on muscle adaptations to resistance training: findings from a randomized clinical trial.
- 2025-10-08
- RCT
- Journal of the International Society of Sports Nutrition 22(1)
- - Martin Hindermann Santini
  - Alice Erwig Leitão
  - Bruna Caruso Mazzolani
  - Fabiana Infante Smaira
  - Mariana Silva Camargo de Souza
  - Andrea Santamaria
  - Bruno Gualano
  - Hamilton Roschel
- PubMed: 41059835
- DOI: 10.1080/15502783.2025.2568047
5 Insights on
- Increased Lean Mass
- High evidence
- Adults
leg lean mass (PLNT: 0.9 kg ±0.2; ANML: 1.3 kg ±0.2)
Effect
Beneficial
Effect size
Moderate
Significant
Yes
Dose
45 g/day (three 15-g daily doses)

Whey Protein and Increased Lean Mass

Explore the Optimal Treatment Regimen Across Combinations of Variate Protein Sources and Exercise Modalities and Its Associated Factors in Older Adults: A Network Meta-Analysis and Meta-Regression of Randomized Controlled Trials.

Whey Protein Supplementation with or without Vitamin D on Sarcopenia-Related Measures: A Systematic Review and Meta-Analysis.

Post-Exercise Whey Protein Supplementation: Effects on IGF-1, Strength, and Body Composition in Pre-Menopausal Women, a Randomised Controlled Trial.

Similar effects between animal-based and plant-based protein blend as complementary dietary protein on muscle adaptations to resistance training: findings from a randomized clinical trial.