Whey vs. Soy Protein: Which Is Better for Lean Muscle Gains?

The muscle-buildling effects of whey and soy protein are compared. See which one comes out on top.

Soy Beans

Many people wonder whether whey or soy protein is the better choice to build lean muscle mass. There's a lot of bad information out there, which may mislead you. My goal is to debunk the myths with research-based facts to help you make the best choices when selecting the type of protein that you want to eat.

A recent study by Yang et al. compared the effects of whey and soy protein in older men (age 71 +/- 5 years). The men completed a single-leg extension exercise before taking either no protein or 20 grams of soy.

The researchers sampled the men's muscle tissue and used fancy scientific equipment to determine the effects and compare the results with those of the non-exercising leg. They found that consuming soy protein was better than nothing, but it did not match the results from earlier studies that used a similar dose of whey protein.

In another study, by Phillips et al., the authors stated, "The data in total suggest that whey supports muscle hypertrophy most effectively in young adults." This was verified by a study performed by Tang JE et al., which stated, "whey hydrolysate stimulated MPS (muscle protein synthesis) to a greater degree than soy after resistance exercise."

Having a bit of soy is not going to make you spontaneously combust, but don't use it as a supplement on a routine basis if you are looking to maximize protein synthesis for bigger and stronger muscles. If for some reason you can't use whey, then soy is better than no protein at all.

Learn more about protein through the STACK Protein Guide.


Phillips SM, Tang JE, Moore DR. "The role of milk- and soy-based protein in support of muscle protein synthesis and muscle protein accretion in young and elderly persons." J Am Coll Nutr. 2009 Aug;28(4):343-54

Tang JE, Moore DR, Kujbida GW, Tarnopolsky MA, Phillips SM. "Ingestion of whey ydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men." J Appl Physiol. 2009 Sep;107(3):987-92. Epub 2009 Jul 9

Yang Y, Churchward-Venne TA, Burd NA, Breen L, Tarnopolsky MA, Phillips SM. "Myofibrillar protein synthesis following ingestion of soy protein isolate at rest and after resistance exercise in elderly men." Nutr Metab (Lond). 2012 Jun 14;9(1):57. [Epub ahead of print]

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