Does soy protein work as well as whey for building muscle?
No Significant Differences in Muscle Growth and Strength Development When Consuming Soy and Whey Protein Supplements Matched for Leucine Following a 12 Week Resistance Training Program in Men and Women: A Randomized Trial
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Soy protein performed equally to whey despite being plant-based and slower-digesting.
Whey is long considered the gold standard for muscle building due to its fast absorption and high leucine. Many assume plant proteins are inferior, but here, soy matched whey when leucine was equalized.
Practical Takeaways
Choose protein supplements with at least 2g of leucine per serving, whether plant or animal-based.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Soy protein performed equally to whey despite being plant-based and slower-digesting.
Whey is long considered the gold standard for muscle building due to its fast absorption and high leucine. Many assume plant proteins are inferior, but here, soy matched whey when leucine was equalized.
Practical Takeaways
Choose protein supplements with at least 2g of leucine per serving, whether plant or animal-based.
Publication
Journal
International Journal of Environmental Research and Public Health
Year
2020
Authors
Heidi M. Lynch, M. Buman, J. Dickinson, L. Ransdell, C. Johnston, Christopher M. Wharton
Related Content
Claims (5)
If you eat the same amount of protein and lift weights the same way, it doesn’t matter whether your protein is fast- or slow-digesting—even if it’s from plants like soy—your muscle gains will be about the same.
If young adults who aren't used to working out do strength training 3 times a week for 12 weeks, they’ll gain about 1.5 kg of muscle and get stronger legs — and it doesn’t matter if their protein shake is made from soy or whey, as long as both have the same amount of leucine (2 grams per day).
For young people new to lifting weights, taking soy protein or whey protein daily seems to have the same effect on thigh muscle growth.
If young adults who aren't used to working out eat a bit more protein—especially from whey or soy—and lift weights 3 times a week for 3 months, they’ll likely gain more muscle and get stronger, even if they weren’t eating enough protein to start with.
If you're a young adult just starting strength training, drinking a shake with either whey or soy protein—both with the same amount of a key muscle-building amino acid (leucine)—will help you gain muscle equally well over 12 weeks.