If you visit a muscle building forum, you will undoubtedly see a few threads full of people arguing about the pros and cons of soy versus whey protein for muscle building purposes. So in this article, I'm going to try and sort it out once and for all. It's a pretty simple issue really, so it won't take long to get to the truth.

The Biological Value indicates both how digestible the protein is and how available the protein is for use by the body. Biological value began as a percentage - A whole egg rated at 100% nitrogen absorbed. According to the study conducted by a medical doctor by the name of Aaron Tabor, soy protein versus whey protein has a bigger advantage especially when it comes to your exercise.

Basically, there are a couple of different protein powders. Whey protein is derived from cows milk. Remember that old nursery rhyme, Incy Wincy Spider Well that mentions curds and whey. Basically two parts of milk. Whey protein is obviously taken from the whey part of the milk.

Then theres soy protein. This is the stuff that is made from soy products. Obviously comes from a different place so it will obviously have different properties. The question you want answered is, which is better for muscle building

My answer to this question is whey protein. The answer can get quite involved when you look at it from a scientific point of view, but I'm not a scientist, I'm a bodybuilder, so I'm going to look at it from a bodybuilders point of view )

Basically, it has been shown in various scientific studies that soy protein can lead to higher levels of estrogen in the body. This is the female hormone and something that you don't want to have more of if you are looking at building muscle.

Firstly, you don't want estrogen because it has no role in muscle building, it only has a negative impact. Heightened levels of estrogen is what actually causes gynocomastia, or man boobs. And I'm not just talking about the little bit of fat that some guys have, I'm talking about actually growing small amounts of breast tissue.

On the other hand, whey protein can actually cause your body to become more anabolic. Meaning it will build muscle more efficiently. And since you are looking to use whey protein for muscle building, this is the one you want to choose.

So there you go, the debate can finally be ended and you can get rid of that tub of soy protein you have sitting in your cupboard.