“Plant protein builds less muscle than whey protein.”
Soy protein builds about as much muscle as whey, while other plant proteins such as rice, oat and potato have built slightly less.
If you prefer plant protein, soy has the strongest record of matching whey for muscle growth. With other plant proteins, any gap looks small and rests on few trials, and getting enough total protein matters more than the source.
Choose a protein you tolerate and will use consistently. If you want a plant option that has matched whey in trials, choose soy.
A 2025 review of randomized trials found that soy built about the same muscle as milk protein across 17 trials, while other plant proteins and fully plant-based diets built slightly less. The answer changes with the type of plant protein, and the non-soy results come from only 12 trials, so confidence is moderate.
Soy protein builds about as much muscle as whey, while other plant proteins such as rice, oat and potato have built slightly less. In a 2025 review of randomized trials, soy matched milk protein across 17 trials, while other plant proteins and fully plant-based diets did a little worse, based on only 12 trials. In one 12-week study, young men on a vegan diet with soy, at about 0.7 grams of protein per pound of body weight a day, gained as much muscle and strength as meat eaters using whey.
Across all 30 trials in the 2025 review, animal protein had a small overall edge for muscle mass, mostly in adults under 60. In adults 60 and older there was no clear difference. Strength (14 trials) and physical performance (5 trials) did not differ between plant and animal protein. The trials compared plant protein with animal protein in general, not only with whey.
Can plant protein support muscle growth from strength training?
Yes. People using plant protein gained muscle in training trials, and across 17 trials soy matched milk protein overall.
- Reid-McCann RJ, Brennan SF, Ward NA, Logan D, McKinley MC, McEvoy CT. Effect of Plant Versus Animal Protein on Muscle Mass, Strength, Physical Performance, and Sarcopenia: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Nutrition Reviews. 2025;83(7):e1581-e1603. DOI: 10.1093/nutrit/nuae200. PMID: 39813010. PMCID: PMC12166177
- Hevia-Larraín V, Gualano B, Longobardi I, Gil S, Fernandes AL, Costa LAR, Pereira RMR, Artioli GG, Phillips SM, Roschel H. High-Protein Plant-Based Diet Versus a Protein-Matched Omnivorous Diet to Support Resistance Training Adaptations: A Comparison Between Habitual Vegans and Omnivores. Sports Medicine. 2021;51(6):1317-1330. DOI: 10.1007/s40279-021-01434-9. PMID: 33599941