Is Soy Protein Effective for Building Muscle?

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Soy protein is an interest addition to the supplement world. It is basically the protein from soybeans that has been isolated and is produced in a powdered form. While the protein itself has been around since the 1960’s and incorporated into food, it wasn’t until the 80’s and 90’s that it became a more common and popular protein option as a soy protein effective for building muscle

As many vegan and health conscious lifters look for the best options to include protein in their diet, soy based protein powders became very popular in the 1990’s along with soy based foods such tofu. So how effective is this type of protein?

Let’s break it down.

The Soy Protein Basics

Most standard soy protein additives are isolates made from soy flour that has been defatted. As the name implies, defatted means the fat has been moved from it. The result is a product that has a great ratio of about 70% protein with around 20% carbs and the rest miscellaneous ash and oil. While ‘ash’ may sound worrisome, it is just a term for residue that you don’t even really notice.

It gets the label of a ‘complete protein’ which means it has all of the essential amino acids we use. It is inexpensive and is used a lot by the food industry in other foods. It rates very highly on the protein value scale and soybean protein, soy milk, and other soy products are usually within the 75 to 100 score rating depending on what they are mixed with. Generally speaking soy protein is easy to digest and gives us almost everything we need from a protein source. Because it is the highest scoring vegetable-based protein, the vegan and vegetarian crowd loves it.

Is it Effective?

Soy protein is just as effective as most other high quality protein sources. As it is easily digestible and has a full slate of amino acids it ranks highly along with eggs and other sources in the 90 to 100 score range. While not as good as whey protein from a scoring standpoint, it still will provide your body with all the building blocks you need for making your muscles bigger and stronger.


There are some issues with soy based proteins, mostly in the context of protein powders. There have been some studies by doctors that indicate thyroid hormone levels have been influenced by a high soy protein diet. But this seems to be an issue of individuals versus everyone as a whole. However if you develop issues relating to your thyroid, digestion, or hormones then soy might be a culprit.

Also there has been a discussion over using fermented soy products versus non-fermented products. With studies on both sides of the fence it has been difficult to nail down risks versus rewards. On the plus side for soy the Asian population is used as an example. But they often use fermented soy and use smaller amounts such as 10 grams per day only. The other side of the fence mentions that we feed unfermented soy to animals and use it in non-food products.

The Bottom Line

Soy protein is effective in building muscle. It has all the nutrients you need. However you should look at exactly what it is you are taking in if it is a protein powder (versus a flour that you might mix in with other foods) and keep track of your body’s reaction. If you start noticing some issues it might be that soy protein is not the right option for you.

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