Which is better, soy protein or whey protein?

Abstract: There are many different types of protein powder on the market, and each type also has different effects. Many people often ask, what is the difference between different protein powders? So today we will talk about the difference between the two most common protein powders-whey protein concentrate and soy protein isolate?

Keywords: soy protein, whey protein

Related products for this article: soy protein


1. Soy VS Whey

Whey protein is concentrated from amino acids isolated from milk. Because of its high amino acid content and ratio, it has been highly praised by sports and nutrition circles.

Soybeans, also called soybeans or edamame, are one of the plant crops with the highest protein content that we can eat in our lives. As the name suggests, soy protein is extracted from soybeans.

For a long time, whey protein has been the star product of resistance training supplements on the market. When everyone mentions protein powder, they usually default to whey protein.

However, in recent years, many people have begun to advocate soy protein. Especially because it is a plant protein and a whole herb extract, it is highly respected by many women.

So, from the point of view of promoting fitness effect and nutrition, which protein powder is better?

2. Protein, who is stronger

First, let’s take a look at the protein content of these two protein powders. This is the simplest and crudest evaluation. That is, compare two protein powders of the same weight, which protein content is higher.

After the Kjeldahl method, the protein conversion factor of whey protein was 6.38, and that of soybean protein isolate was 5.71.

(Kjeldahl method: a commonly used method in analytical chemistry to determine the nitrogen content of organic compounds. Since the nitrogen content of protein is relatively constant, the protein content can be calculated from its nitrogen content, so it is also a classic protein quantification method. )

Of course, it is unscientific to simply look at the protein content, we also have to look at the ratio of amino acids. Modern nutrition emphasizes the balance of amino acids. The deficiency or excess of certain amino acids will affect the value of protein powder. In this regard, scholars have specifically studied the composition of the two protein powders and the ratio of essential amino acids required by the human body, and obtained the amino acid ratio coefficients of the two protein powders.

From the perspective of nutritional value, whey protein is better than soy protein, whether it is protein content or amino acid ratio, and is more suitable for the human body.

3. Whey protein, better muscle growth

Different types of protein powder will have different effects on human hormones. Scientists compared the different changes in body hormones produced by resistance training for 12 weeks, combined with whey protein and soy protein.

The data showed that the ratio of testosterone to estrogen was significantly higher in subjects taking the whey protein group (researchers believe this is related to the activity of the enzyme system). In other words, for people who want to gain muscle and lose fat through strength training, whey protein may have a better effect.

Whey Protein


In resistance training, the ratio of testosterone to estrogen can significantly affect the effect of muscle gain and fat loss. Simply put, testosterone can promote muscle and strength growth, and estrogen may accumulate fat.

The whey protein group has higher testosterone and lower estrogen, which is more conducive to muscle gain and fat loss.

After being ingested by the human body, soy protein will enter the internal organs first, while milk protein (including whey, casein, etc.) will enter the muscle tissue first. This means that whey protein, as a supplement after strength training, may work faster.

4. Whey protein is more conducive to fat loss

From the perspective of fat reduction, the calories of whey protein and soy protein are almost the same. Some brands of whey protein have much lower calories than soy protein. Supplementing the same amount of protein can also consume less calories. .

Moreover, for children’s shoes who want to reduce fat through resistance training, whey protein has some other benefits. For example, whey protein has a large amount of branched chain amino acid BCAA. Intake of BCAA before and after exercise can ensure that the body is in It consumes fat and does not lose muscle. It is more suitable for people who need a lot of fat and weight loss.

In general, as a protein supplement after resistance training, whey protein is more suitable for muscle gain and fat reduction than soy protein.