Pros And Cons + Which Is Better

Anyone interested in fitness will have definitely come across the soy protein vs. whey protein debate. Soy and whey proteins are the two common supplements fitness enthusiasts usually research on during their journey. Though similar in their nutritional composition, the two are different in their functions, digestibility, and benefits.

What makes them different from each other? Which one should you choose for your health? These are important questions that need answers. In this article, you will learn about the major differences between the two protein variants, their pros and cons, and which of the two is better for you. Keep reading.

What Is Soy Protein?

Soy protein is a plant-based protein made from soya beans. The soya beans are ground into a fine meal before its fiber, carbohydrate, and fat are removed. The manufacturers then grind and process the remaining powder into soy flour, soy protein concentrate, or soy protein isolate, which contain all the nine essential amino acids, glutamine, and arginine. Soy protein isolate is the most refined of all, as it contains about 88.3 g protein for every 100 gm serving (1). Increasing soy protein intake may help lower total cholesterol levels, low-density lipoprotein, and triglyceridesi  XA type of fat produced in the body and stored in the blood to provide energy in between meals. . It also can relieve menopausal hot flashesi  XSwearing and a sudden intense warmth spreading over the neck, face, and chest that occurs mainly during the menopausal stage. , maintain bone density, control obesity, and decrease fractures in postmenopausal women (2), (3).

Related: 15 Homemade Protein Shakes – Healthy & Tasty 5-Min Recipes

What Is Whey Protein?

Whey protein is an animal-based protein obtained from cow’s milk. It is formed as a byproduct of the cheesemaking process. When cheese is made from cow’s milk, the casein gets separated and leaves behind whey protein and water as byproducts. The water is then processed to make concentrated whey isolate, which has a high percentage of pure protein at 58.1 g per 100 gm serving. Carbohydrates, fats, and cholesterol are present, though only in limited amounts (4). Whey protein supplementation helps improve body weight and total fat mass and reduces the risk of cardiovascular disease in those dealing with obesity (5).

Did You Know?

Legend has it that, during the Middle Ages, a medical tonic made from whey protein was used to treat ailing patients.

Most people use both these proteins to control obesity and improve body composition. However, they are not the same. Apart from their sources, there are other differences that make these two variants unique in their own right.

Differences Between Soy And Whey Protein

Soy Protein Vs. Whey Protein: Taste And Texture

Soy protein drinks are grainier and have a stronger nutty flavor than those made with whey protein. Whey protein drinks have a creamier and smoother texture with a mildly nutty flavor. However, the taste and texture also depend on the different brands and the flavors they use.

Health Related Information says

You can buy unflavored versions of protein and create your own taste by adding fruits and nuts of your choice.

Soy Protein Vs. Whey Protein: Biological Values

Biological values highlight how efficiently the body utilizes the protein consumed through the diet. Whey, at 104, scores higher in this regard; while soy scores 74 (6). This score suggests that the amount of protein absorbed from whey protein is more than that from soy protein.

Soy Protein Vs. Whey Protein: Net Protein Utilization

Net protein utilization also measures the value or usefulness of specific proteins in a diet. It is the ratio of amino acids converted to protein to the mass of amino acids supplied. Here, too, whey scores higher at 92 while soy protein is at 61 (6).

Soy Protein Vs. Whey Protein: Amino Acids

Soy protein and whey protein are complete proteins that contain all essential amino acids. However, they are not distributed equally. While soy protein is high in histidine and phenylamine, whey protein has the highest percentage of leucine, isoleucine, methionine, threonine, and lysine (7).

Essential Amino Acids Soy (per 100 g) Whey (per 100 g)








Total EAA




















Non-Essential Amino Acids Soy (per 100 g) Whey (per 100 g)


Glutamic acid






Total NEAA



















While these amino acids help improve several health parameters, if not used properly, they may also cause adverse effects. Read on to find out more.

Pros And Cons Of Soy Protein And Whey Protein

Soy Protein


  • Is a complete, vegan protein source.
  • A good source of fiber, iron, calcium, zinc, and B vitamins.
  • Isoflavonesi  XPlant-based compounds found mainly in soy products that may protect against age-related health issues. in soy products bind to estrogen receptors to help lower cholesterol levels (3).
  • Dietary intervention of soy protein improves blood glucose levels, insulin resistance, and obesity (8).
  • Genisteini  XA compound developed from legumes that helps inhibit estrogen and reduce blood glucose levels. in soy may help reduce the risk of cancer.
  • Its phytoestrogensi  XEstrogen-like compounds present naturally in plants that have a similar chemical structure to the body’s estrogens. help protect women from bone loss and heart disease.


  • Trypsin inhibitorsi  XA protein and type of inhibitor that controls the activation and reaction of the enzyme trypsin and other proteins. in soy may reduce protein digestibility (9).
  • Lectins and lysinoalanine formed during the processing of soybeans may cause allergic reactions (10).
  • Isoflavones and phytoestrogens in soy products may result in lower sperm concentration (11).

Whey Protein


  • Is a complete protein source.
  • Prebiotic properties help improve intestinal disorders and reduce obesity risk (12).
  • Its high protein, low-carbohydrate content may provide health benefits for people with diabetes (13).
  • Has a higher concentration of essential amino acids and can be digested efficiently (14).
  • Its bioactive compounds can also help improve body weight and total fat mass and reduce risk of cardiovascular disease (5).


  • Not an option for vegans.
  • Its high lactose content may cause adverse effects in those with lactose intolerance (15).
  • Excess, chronic use may cause kidney and liver damage (16).

Knowing the pros and cons of both soy and whey protein can help you choose the best for your health. Read on to know how to settle the debate.

Which Is Better: Whey Or Soy Protein?

You need to consider certain parameters to choose one of the two. These include protein quality, digestibility, and health benefits.

Protein quality: The quantity of essential amino acids, biological values, and net protein utilization values discussed show us that whey protein offers better quality protein.

Absorption and digestion: The digestibility and absorption of nutrients and protein from whey protein is better than that of soy protein (17).

Weight loss: In a study, those who consumed whey protein showed a larger difference in body weight and fat mass compared to those who received soy protein (18).

However, both soy and whey protein show equally good results in some aspects. The two protein variants help enhance muscle recovery, reduce soreness after training, and improve muscle strength (19), (20), (21).

Though whey protein is the clear winner in terms of higher protein quality and digestibility, it is best to choose a variant based on your body’s requirements and under the guidance of a physical trainer or medical professional.

Final Words

The soy protein vs. whey protein debate may go on. Though they are derived from two entirely different sources, both are complete proteins with all the essential amino acids. This makes them a healthy addition to your diet. However, in terms of overall quality, whey protein is often regarded as superior. Nevertheless, the side effects of these two proteins and potential allergic reactions also need to be considered. Hence, consult your doctor or trainer to seek guidance before you pick a product for yourself.

Frequently Asked Questions

Is whey better than soy for increasing testosterone?

Yes, whey protein increases testosterone more than soy protein. In a study on 10 male athletes, men on soy protein had lower levels of testosterone (22). Another study showed that consuming whey protein can help boost testosterone levels in older men (23).

Do soybeans increase breast size?

Soybeans or soy proteins may mimic the effects of estrogen (24). However, there is no evidence suggesting that they increase breast size.

Does soy raise estrogen in males?

No, soy protein does not raise estrogen in males. As per one study conducted on 10 male athletes, the group consuming soy protein did not show any increase in estradiol (estrogen) concentrations (22).

Key Takeaways

  • Whey protein and soy protein are animal and plant proteins, respectively.
  • While whey protein is derived from milk, soy protein is derived from soya beans.
  • They both contain all the necessary amino acids, only differing in quality and quantity.
  • Whey protein helps in weight loss better than soy protein, though both help equally well in muscle recovery and development.