Is Isolated Soy Protein Good for Building Muscle?
Abstract: In the world of bodybuilding, protein is a big deal. You need protein to help your muscles to rebuild and repair themselves after a workout. While foods like beef, tuna, eggs and chicken, along with dairy-based protein powders, are often seen as the go-to muscle-building foods and supplements, those on a plant-based diet may need to look to other ways to get protein, such as with soy protein in food and supplement form.
Keywords: isolated soy protein

Is soy protein isolate suitable for muscle gain?
Of course, soy protein isolate can build muscle. As long as it is protein, it is good for muscle growth. Because muscle is mainly composed of protein, you can also eat tofu, rice, and eggs every day. Soy protein isolate can be taken at ordinary times, but the prime time should be taken within 20 minutes after exercise to allow the muscles to be fully stretched and quickly replenish when the muscles begin to grow.
The Soy and Estrogen Myth
One of the reasons why many wannabe muscle-builders avoid soy protein is because of a belief that soy will increase estrogen and reduce testosterone levels, slowing down muscle growth. A meta analysis published in a 2010 edition of the journal of “Fertility and Sterility,” however, concluded that neither soy-based foods nor supplements have a negative impact on testosterone levels.
Soy Vs. Whey Vs. Casein
When compared to whey and casein protein supplements, soy protein powder sits somewhere in the middle in terms of muscle protein synthesis. This is the speed at which protein is used by the muscles, and a higher protein synthesis is beneficial for building muscle. In a study from a 2009 edition of the “Journal of Applied Physiology,” soy protein supplementation was inferior to whey hydrolysate in terms of synthesizing protein for muscle, but it performed better than casein protein.
Soy: The Complete Package
When compared to whey and casein protein supplements, soy protein powder sits somewhere in the middle in terms of muscle protein synthesis. This is the speed at which protein is used by the muscles, and a higher protein synthesis is beneficial for building muscle. In a study from a 2009 edition of the “Journal of Applied Physiology,” soy protein supplementation was inferior to whey hydrolysate in terms of synthesizing protein for muscle, but it performed better than casein protein.
Soy Foods and Non-Soy Supplements
Soy protein can come from different foods, such as soy milk, tofu and edamame, as well as special soy protein powders. Vegan strength athletes and bodybuilders often consume a lot of soy-based foods, notes nutritionist Ryan Andrews, which is fine, but when picking a supplement, you may want to look to a plant-based protein powder not made from soy, to avoid overloading on a single source. Brown rice, hemp and pea protein are all other options.