Difference Between Whey Protein and Soy Protein

The main difference between whey protein and soy protein is that whey protein is a milk-based product whereas soy protein is a plant-based product. Further, Whey proteins contain a higher protein content than soy protein. Whey protein may contain a significant amount of fat while soy protein is relatively low in fat.

Whey protein and soy protein are the two most popular protein sources when having a protein-rich diet. Whey protein is a by-product of cheese while soy protein is the only plant-based protein supplement extracted from soybean, a type of legume.

Key Areas Covered

1. What is Whey Protein
      – Definition, Components, Health Effects, Types
2. What is Soy Protein
     – Definition, Components, Health Effects, Types
3. What are the Similarities Between Whey Protein and Soy Protein
     – Outline of Common Features
4. What is the Difference Between Whey Protein and Soy Protein
     – Comparison of Key Differences 

Key Terms: Fat, Health Effects, Protein Content, Soy Protein, Whey ProteinDifference Between Whey and Soy Protein - Comparison Summary

What is Whey Protein

Whey protein contains a mixture of globular proteins isolated from whey. Whey refers to the liquid material, which is the leftover of the coagulation procedure of cheese production. That means, it contains the soluble components of milk at pH 4.6. Whey is processed to increase the protein content, either by drying or removing fat and carbohydrates. 

Components of Whey Protein

1. Alpha- and beta-lactoglobulin

2. Bovine serum albumin

3. Immunoglobulins

4. Other components: iron-binding proteins (lactoferrin, lactoferricin), calcium, potassium, sodium, phosphorus, folic acid, biotin, and vitamin A, C, B1, B2, B3, B5, and B12.

Difference Between Whey Protein and Soy Protein

Figure 1: Whey Protein Drink

The three types of whey protein in the market are concentrate, isolate, and hydrolysate.

1. Whey protein concentrate (WPC) – WPC contains 80% of whey protein by weight. Also, it contains a higher amount of carbohydrate in the form of lactose and significant levels of fat and cholesterol. 

2. Whey protein isolate (WPI) – WPI contains 90% of whey protein by weight and fat and lactose removed during the processing.  

3. Whey protein hydrolysate (WPH) – WPH contains pre-digested and partially hydrolyzed whey protein. WPH is easy to digest. Highly hydrolyzed form of WPH is the least allergenic. 

Whey protein is readily absorbable by the body, and therefore, an effective protein supplement. However, it may cause milk allergies.

Health Effects

1. Increase satiety and reduces energy intake

2. Helps to maintain or archive normal body weight

3. Helps to increase or maintain muscle mass

4. Reduce body fat mass during energy restriction

5. Help to increase the muscle strength

6. Increases endurance capacity during the subsequent exercise

7. Repairs skeletal muscle tissue

8. Helps to recover from muscle fatigue faster after exercise

What is Soy Protein

Soy protein refers to proteins isolated from soybean. The dehulled and defatted soybean is ground to prepare the soybean meal. Soy protein contains a fewer amount of protein when compared to whey protein, which is denoted by its biological value. However, soy contains very low fat, and it does not contain cholesterol.

Components of Soy Protein

1. Protein

2. Essential fatty acids (omega-3)

3. Phytosterols and lecithin

4. Fiber components

5. Isoflavones

6. Protease inhibitors

7. Other components: zinc, iron, phosphorus, potassium, B complex vitamin, and vitamin E

Main Difference - whey protein and Soy Protein

Figure 2: Soybean

Based on further processing steps, three types of soy protein products are available in the market. They are soy flour, concentrates, and isolates.

1. Soy flour – It is the ground soybean into a fine powder. It contains 50% protein by weight. The three forms of soy flour available are whole or full-fat (with natural oils), defatted (oils removed), and lecithinated (lecithin added).

2. Soy protein concentrate – It contains around 70% of soy protein. It is generally defatted and does not contain water-soluble carbohydrates. A common of use this is in the baked food products.

3. Soy protein isolate – It contains 90% of protein by dry weight and does not contain any fat or carbohydrate.

Health Effects 

1. A significant decrease in serum cholesterol, LDL, and triglycerides

2. A good source of proteins for vegans

3. Better for individuals with lactose intolerance

Similarities Between Whey and Soy Protein

  • Whey and soy protein are complete proteins, containing all essential amino acids.
  • Both are high in their protein content.
  • Isolate protein of both types contain more than 90% of protein by weight.
  • Both serve as dietary supplements of protein.
  • These two types of proteins increase lean muscle mass in same amounts.
  • They have a shelf life of more than one year.

Difference Between Whey Protein and Soy Protein


Whey protein: A mixture of globular proteins isolated from whey

Soy protein: Proteins isolated from soybean


Whey protein: Animal source – milk

Soy protein: Plant source – soybean


Whey protein: Dried leftover from the cheese production

Soy protein: Production involves grinding soybean and processing 

Available Forms

Whey protein: Whey protein concentrate, isolate, and hydrolysate

Soy Protein: Soy flour, concentrate, and isolate


Whey protein: Smooth and creamy

Soy protein: Grainier


Whey protein: Mildly nutty taste

Soy protein: Stronger nutty taste

Biological Value

Whey protein: 104

Soy protein: 74

Major Essential Amino Acids Present

Whey protein: Higher in methionine, leucine, isoleucine, and lysine

Soy protein: Higher in phenylalanine, arginine, and tryptophan


Whey protein: Contain a significant level of milk fat

Soy protein: Contain less fat or defatted


Whey protein: Contain lactose

Soy protein: Do not contain lactose; carbohydrates in the form of fiber

Testosterone Response

Whey protein: High testosterone response

Soy protein: Low testosterone response

Health Benefits

Whey protein: Maybe allergenic

Soy protein: Best for lactose intolerance


Whey protein is a milk-based product while soy protein is a plant-based product. Whey protein is a processed by-product of cheese production. Soy protein is the ground soybean. Whey protein consists of higher amounts of proteins when compared to soy protein. The main difference between whey protein and soy protein is the source of each product.


1. Kendall, Krissy. “Your Expert Guide To Whey Protein.” Bodybuilding.com, 12 Apr. 2018, 
2. Robson, David. “Soy: Friend Or Foe?” Bodybuilding.com, 19 Apr. 2018, 

Image Courtesy:

1. “Hmmm Proteinicious” By Adam Pieniazek  via
2. “853093” (CC0) via

About the Author: Lakna

Lakna, a graduate in Molecular Biology & Biochemistry, is a Molecular Biologist and has a broad and keen interest in the discovery of nature related things

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