Soy Protein vs Whey Protein Key Points

  • The review analyzed the effects of soy protein vs whey protein, and other animal proteins on muscle mass and strength gains.
  • The meta-analysis results indicate that supplementation with soy protein during resistance training leads to similar increases in muscle mass and strength compared to whey protein and other animal proteins.
  • For individuals looking to gain muscle, the practical applications of the study suggest that protein supplementation, regardless of the source (such as soy protein vs whey protein), can effectively increase lean body mass and strength when combined with resistance exercise training.

Introduction to Plant-Based Proteins

Have you ever stood in the health supplement aisle, staring at the vast array of protein powders and wondering which is best for muscle growth? You’re not alone. For years, the fitness world has been engaged in a heated debate: soy protein or whey protein for muscle building? This article will explore the science behind a new review titled “No Difference Between the Effects of Supplementing with Soy Protein Versus Animal Protein on Gains in Muscle Mass and Strength in Response to Resistance Exercise.” 

This article will explore the differences between plant and animal proteins, specifically focusing on soy and whey protein concentrate. By the end of this blog, you’ll have all the information you need to make an informed decision about soy protein vs. whey protein concentrate for muscle building.

Nutrition, Vegan Foods, and Absorption:

Before diving into the soy vs. whey debate, it’s essential to understand the role of protein supplements in muscle growth. Proteins are made up of amino acids, often called the building blocks of muscles. When you consume protein, your body breaks it down into amino acids, which are used to repair and build new muscle fibers. This process is known as muscle protein synthesis (MPS), and it’s the key to muscle growth and recovery.

Amino acids are the building blocks of proteins, and approximately 20 amino acids are essential for forming body proteins. Among these essential amino acids, leucine has been extensively studied for its role in stimulating muscle protein synthesis. Leucine-enriched nutrients have been shown to regulate the mammalian target of rapamycin (mTOR) signaling pathway, which is involved in muscle protein synthesis (Drummond & Rasmussen, 2008).

a blender filled with ingredients to make a smoothie

Studies have demonstrated that leucine supplementation can enhance muscle anabolism and improve net protein balance. (Glynn et al., 2010) However, excessive leucine intake may not further enhance net protein anabolism. The International Society of Sports Nutrition recommends that the postexercise meal contain as much as 3 g of leucine and a balanced array of indispensable amino acids (IAAs). (Jäger et al., 2017)

Plant Proteins vs. Animal Proteins: The Impact on Muscle Hypertrophy and Resistance Exercise

Animal proteins, such as meat, contain all essential amino acids and are considered high-quality proteins. Animal-based proteins have been shown to elicit a higher muscle protein synthetic response compared to plant-based proteins. (Vliet et al., 2015) The higher anabolic properties of animal proteins may be attributed to their superior digestibility and amino acid profile.

Plant proteins, such as soy, have been shown to have numerous health benefits, including lowering blood cholesterol levels. However, within the sports nutrition community, there’s a prevailing view that animal proteins, particularly whey protein, are more effective in promoting muscle growth in response to resistance exercise training (Devries & Phillips, 2015; Hulmi et al., 2010; van Vliet et al., 2015).

Effect of Leucine, Plant Proteins, Hypertrophy and Protein Synthesis

Plant-based diets have gained popularity due to their cardiovascular and environmental benefits. Many athletes are concerned that plant-based diets may lead to a loss of lean muscle mass due to insufficient protein content (Hegde & Roberts, 2022).

Plant proteins differ from animal proteins in their amino acid composition. While animal proteins contain all nine essential amino acids, plant proteins may lack certain essential amino acids, such as leucine, lysine, and methionine. (Pinckaers et al., 2022) This difference in amino acid composition has led to the belief that plant proteins may have lesser anabolic properties than animal proteins.

Recent studies have investigated the muscle protein synthetic response to plant-derived protein blends and compared them to milk protein. The findings suggest that the rise in muscle protein synthesis rates following the ingestion of plant-derived protein blends is comparable to that of milk protein. This indicates that combining different plant-derived proteins can provide a more balanced amino acid profile, potentially enhancing their anabolic properties (Pinckaers et al., 2022).

The Soy Supplement Story: More Than Just a Plant Protein

Soy protein vs whey proteinSoy vs whey protein Whey vs soy protein Soy protein vs whey soy protein muscle Evidence based muscle

Soy protein has been a staple in many diets worldwide, particularly in Asia, for thousands of years. It’s derived from soybeans, a legume native to East Asia. Soy protein is unique among plant proteins because it’s considered a complete protein. This means it contains all nine essential amino acids that our bodies can’t produce independently. (Hughes et al., 2011) These amino acids are crucial for various bodily functions, including muscle repair and growth.

Soy consumption has been associated with numerous health benefits. Epidemiological studies have linked soy intake to a reduced risk of chronic diseases, including cardiovascular diseases, certain types of cancer, and osteoporosis. (Kang et al., 2010)

Soy isoflavones, in particular, have received considerable attention for their potential health effects. They have been suggested to contribute to the reported health benefits of soy foods and have been associated with a lower risk or prevalence of cognitive impairment. (Koch et al., 2021) Moreover, soy protein has been approved for a health claim regarding its ability to reduce the risk of coronary heart disease. (Koch et al., 2021)

The Estrogen Con: Debunking the Feminization Myth – Is Soy Bad for Muscle Growth?

One of the most common myths about soy protein is that it’s feminizing for men. This myth stems from soy-containing isoflavones, a type of phytoestrogen. Phytoestrogens are plant-derived compounds that can interact with estrogen receptors in the human body, leading some to worry about potential feminizing effects. A comprehensive review of 15 studies found no evidence that soy protein or isoflavones adversely affect testosterone or estrogen levels in men. (Hamilton-Reeves et al., 2010)

The Muscle Mass Mystery: Soy Protein vs Whey Protein for Muscle Building

Now, let’s get to the heart of muscle growth. Some believe soy protein is inferior to whey protein because it has lower amounts of leucine, an essential amino acid that plays a key role in muscle protein synthesis. However, muscle hypertrophy is a complex process, and current research reveals that total protein intake is much more important for muscle hypertrophy than acute protein synthesis rates. (Damas et al., 2016)

Recent research suggests that the total daily protein intake is the most potent factor in maximizing muscle adaptation in conjunction with resistance training. (Joy et al., 2018) Therefore, focusing on meeting daily protein requirements rather than specific timing may be more important for muscle hypertrophy.(Morton et al., 2018)

The Verdict: Unveiling the Truth – Whey Protein vs Soy Protein

A 2018 meta-analysis published in the International Journal of Sports Nutrition and Exercise Metabolism compared soy protein versus animal protein for increased muscle mass and strength in response to resistance exercise. The results? No differences. That’s right; soy protein supplementation produces similar gains in strength and lean mass in response to resistance training as whey protein. (Messina et al., 2018) The article recommended consuming a soy protein dose of approximately 38 g of soy protein to maximize protein synthesis.

The Protein Puzzle Solved – Is Soy Protein Good for Muscle Building?

Soy protein vs whey proteinSoy vs whey protein Whey vs soy protein Soy protein vs whey soy protein muscle Evidence based muscle

So, what’s the takeaway from all this? Even though whey protein results in acutely greater protein synthesis, long-term studies have found no differences in muscle mass or strength when comparing soy to whey protein. Therefore, soy protein is a viable option for muscle building and a powerful one that stands on equal footing with its animal-based counterparts. So next time you find yourself in the health supplement aisle, remember: the choice between soy and whey isn’t as puzzling as it seems.

In conclusion, while acute studies showed that when matched for nitrogen content, soy protein stimulates muscle protein synthesis to a lesser extent than whey protein, these differences have led to speculation that soy protein is inferior to milk and whey protein in building muscle and increasing strength in response to resistance exercise training (Devries & Phillips, 2015; Jäger et al., 2017]. However, the results of the current meta-analysis do not support such speculation as strength (bench press and squat), and lean tissue accretion in response to RET were similar between whey and soy protein supplementation.


Damas, F., Phillips, S. M., Libardi, C. A., Vechin, F. C., Lixandrão, M. E., Jannig, P. R., Costa, L. A., Bacurau, A. V., Snijders, T., Parise, G., Tricoli, V., Roschel, H., & Ugrinowitsch, C. (2016). Resistance training-induced changes in integrated myofibrillar protein synthesis are related to hypertrophy only after attenuation of muscle damage. J Physiol, 594(18), 5209-5222.

Devries, M. C., & Phillips, S. M. (2015). Supplemental Protein in Support of Muscle Mass and Health: Advantage Whey. Journal of Food Science, 80(S1), A8-A15.

Drummond, M. J., & Rasmussen, B. B. (2008). Leucine-Enriched Nutrients and the Regulation of Mammalian Target of Rapamycin Signalling and Human Skeletal Muscle Protein Synthesis. Current Opinion in Clinical Nutrition & Metabolic Care.

Glynn, E. L., Fry, C. H., Drummond, M. J., Timmerman, K. L., Dhanani, S., Volpi, E., & Rasmussen, B. B. (2010). Excess Leucine Intake Enhances Muscle Anabolic Signaling but Not Net Protein Anabolism in Young Men and Women. Journal of Nutrition.

Hamilton-Reeves, J. M., Vazquez, G., Duval, S. J., Phipps, W. R., Kurzer, M. S., & Messina, M. J. (2010). Clinical studies show no effects of soy protein or isoflavones on reproductive hormones in men: results of a meta-analysis. Fertil Steril, 94(3), 997-1007.

Hegde, A., & Roberts, A. (2022). Is Plant Protein Equally as Effective at Promoting Lean Muscle Mass Compared to Meat? Journal of Student Research.


Hughes, G. J., Ryan, D. J., Mukherjea, R., & Schasteen, C. S. (2011). Protein digestibility-corrected amino acid scores (PDCAAS) for soy protein isolates and concentrate: criteria for evaluation. J Agric Food Chem, 59(23), 12707-12712.

Hulmi, J. J., Lockwood, C. M., & Stout, J. R. (2010). Effect of protein/essential amino acids and resistance training on skeletal muscle hypertrophy: A case for whey protein. Nutrition & Metabolism, 7(1), 51.

Jäger, R., Kerksick, C. M., Campbell, B. I., Cribb, P. J., Wells, S. D., Skwiat, T. M., Purpura, M., Ziegenfuss, T. N., Ferrando, A. A., Arent, S. M., Smith-Ryan, A. E., Stout, J. R., Arciero, P. J., Ormsbee, M. J., Taylor, L. W., Wilborn, C. D., Kalman, D. S., Kreider, R. B., Willoughby, D. S., . . . Antonio, J. (2017). International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition, 14(1), 20.

Joy, J. M., Vogel, R. M., Broughton, K., Kudla, U., Kerr, N. Y., Davison, J. M., Wildman, R., & DiMarco, N. M. (2018). Daytime and Nighttime Casein Supplements Similarly Increase Muscle Size and Strength in Response to Resistance Training Earlier in the Day: A Preliminary Investigation. Journal of the International Society of Sports Nutrition.

Kang, J., Badger, T. M., Ronis, M. J. J., & Wu, X. (2010). Non-Isoflavone Phytochemicals in Soy and Their Health Effects. Journal of Agricultural and Food Chemistry.

Koch, M., Schlesinger, S., & Schlesinger, S. (2021). Soy Consumption, Cognitive Function, and Dementia. Current Opinion in Lipidology.


Messina, M., Lynch, H., Dickinson, J. M., & Reed, K. E. (2018). No Difference Between the Effects of Supplementing With Soy Protein Versus Animal Protein on Gains in Muscle Mass and Strength in Response to Resistance Exercise. International Journal of Sport Nutrition and Exercise Metabolism, 28(6), 674-685.

Morton, R. W., Murphy, K. T., McKellar, S. R., Schoenfeld, B. J., Henselmans, M., Helms, E., Aragon, A. A., Devries, M. C., Banfield, L., Krieger, J. W., & Phillips, S. M. (2018). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med, 52(6), 376-384.

Pinckaers, P. J. M., Kouw, I. W. K., Gorissen, S. H. M., Houben, L. H. P., Senden, J. M. G., Wodzig, W. K. H. W., Groot, C. P. G. M. d., Verdijk, L. B., Snijders, T., & Loon, L. J. C. v. (2022). The Muscle Protein Synthetic Response to the Ingestion of a Plant-Derived Protein Blend Does Not Differ From an Equivalent Amount of Milk Protein in Healthy Young Males. Journal of Nutrition.

van Vliet, S., Burd, N. A., & van Loon, L. J. (2015). The Skeletal Muscle Anabolic Response to Plant- versus Animal-Based Protein Consumption. J Nutr, 145(9), 1981-1991.

Additional Considerations: Plant Proteins vs Animal Proteins and Muscle Hypertrophy

Soy protein, derived from the humble soybean, has been a staple in many diets, particularly for vegans and those with lactose intolerance. This plant-based protein source is packed with essential nutrients and offers numerous health benefits, making it a popular choice for many health-conscious individuals.

Soy protein is available in various forms, including soy protein isolate, soy protein powder, and more minimally processed options like tofu and tempeh. It can be easily incorporated into your diet through a protein shake or as an ingredient in various recipes.

Protein Quality

One of the main advantages of soy protein is its high protein quality. It is a complete protein containing all the essential amino acids your body needs. This makes it an excellent choice for muscle building and recovery after workouts.

In addition to its protein content, soy protein is also rich in various minerals, such as calcium and zinc, which are essential for bone health and immune function. It also contains isoleucine, valine, and other branched-chain amino acids (BCAAs) that are crucial for muscle growth and repair.

Soy Protein Benefits

Soy protein is also a great option for those looking to lose body weight. It is low in calories and high in fiber, which can help you feel full and satisfied, reducing the likelihood of overeating. Moreover, the enzymes in soy help improve absorption and digestion, further supporting weight loss efforts.

Despite its numerous benefits, soy protein has been the subject of several myths and misconceptions. One of the most common concerns is its phytoestrogen content. However, research has shown that the phytoestrogens in soy do not have the same effects as the estrogen hormone in the body. In fact, they may offer health benefits such as reducing the risk of heart disease and certain types of cancer.

Another advantage of soy protein is that it’s a great alternative for those with dairy allergies or lactose intolerance. Unlike whey protein powder or whey protein isolate derived from cow’s milk, soy protein is plant-based and does not contain lactose, making it easier to digest for those with lactose intolerance.

Soy Can Be Used to Build Muscle

In conclusion, soy protein is a versatile and nutrient-dense protein source that can benefit any diet. Whether you’re a vegan, trying to lose weight, or simply looking to increase your protein intake, soy protein offers a host of benefits that can contribute to your overall well-being.

Higher protein intakes may help to prevent and/or delay the onset of sarcopenia, and because protein is more satiating than carbohydrates and fat, higher protein diets may also help with weight management. In addition to the total protein intake, research has focused on the effects of different types of protein, in particular plant vs animal protein, on the risk of developing various chronic diseases.

Soy Protein Supplements

Soy protein is often considered to be the quintessential plant protein, and as such, it is often compared with animal proteins in various animal and human studies. Plant proteins such as soy protein may have a number of advantages over animal protein, such as lowering blood cholesterol levels; however, a general view within the sports nutrition community is that animal proteins and whey protein, in particular, are more effective in building muscle in response to resistance exercise training.

Some researchers consider whey protein to be superior to soy protein in building muscle and increasing strength, which is not surprising given the results of some studies. However, other studies have found no significant differences in the effects of soy protein and whey protein on muscle protein synthesis (MPS) and muscle hypertrophy.

In conclusion, when comparing soy protein vs whey protein; the evidence suggests that soy protein can be just as effective as whey protein in promoting muscle growth and strength. The key is to consume adequate amounts of protein, regardless of the source. Whether you choose soy or whey protein, both can be part of a healthy diet promoting muscle growth and strength.

Frequently Asked Questions

Can I use both soy protein and whey protein together for optimal muscle gains?

Yes, combining soy protein and whey protein can be beneficial for optimal muscle gains. By using different protein sources, you can get a complete amino acid profile, supporting muscle recovery and growth. However, it’s important to consider your overall protein intake and seek personalized advice from a healthcare professional or nutritionist.

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