To Top


Mixed muscle protein synthesis at rest was higher when the subjects got the faster proteins. In fact, with whey it was about 93 percent greater than with casein and about 18 percent greater than with soy.

Whey remains the protein of choice for body­builders. Scientists recently compared the acute response of mixed muscle protein synthesis to rapidly (whey hydrolysate and soy) and slowly (micellar casein) digested proteins both at rest and after resistance exercise.1 Yep, soy is considered a “fast” protein.

Three groups of healthy young men performed a bout of single-leg resistance exercise and then drank a mixture containing 10 grams of essential amino acids in whey hydrolysate, micellar casein or soy protein isolate. Rather than making the three drinks equal in terms of total protein, the researchers controlled them for the total of essential amino acids. Interesting.

Mixed muscle protein synthesis at rest was higher when the subjects got the faster proteins. In fact, with whey it was about 93 percent greater than with casein and about 18 percent greater than with soy.

A similar result was observed after exercise; muscle protein synthesis following whey intake was approximately 122 percent greater than with casein and 31 percent greater than with soy. Those results confirm another study that looked at protein supplementation over a 10-week training period. Scientists compared the effects of hydrolyzed whey isolate and casein on strength, body composition and plasma glutamine during a 10-week supervised resistance-training program.2 In a double-blind protocol, 13 male recreational bodybuilders supplemented their normal diet with either whey isolate or casein at a dosage of 1.5 grams per kilogram of bodyweight. The whey group gained more lean body mass than the casein group and lost more fat. The whey group also achieved significantly greater improvement in strength than the casein group in each assessment of strength. When the strength changes were expressed relative to bodyweight, the whey group still achieved significantly greater improvement in strength than the casein group.

But here’s the question: Why is there a difference between soy and whey, which are both fast, when the protein doses had the same essential amino acid content? Scientists speculate that the greater total branched-chain amino acid content (about 7 percent more) and leucine content (about 28 percent more) may explain the greater muscle protein synthesis rates with whey.

So leucine might serve as the critical trigger for maximally stimulating protein synthesis. I say, why not just add more BCAAs and leucine to soy or casein? Ah, who has time for that?

There you have it. Training data indicate that whey protein is the more anabolic of the two. As for soy, who gives a hooey about that protein anyhow?

Editor’s note: Jose Antonio, Ph.D., is the CEO of the International Society of Sports Nutrition ( and is a sports science consultant to VPX/Redline. IM


1 Tang, J.E., et al. (2009). Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. J Appl Physiol. In press.

2 Cribb, P.J., et al. (2006). The effect of whey isolate and resistance training on strength, body composition, and plasma glutamine. Int J Sport Nutr Exerc Metab. 6(5):494-509.

Instantized Creatine- Gains In Bulk

You must be logged in to post a comment Login

Leave a Reply

More in Diet & Recipes

  • Green Chile Egg White Cups

    . . Super convenient for meals on the go, killer macros, easy to prep in bulk, and oh so tasty!  ...

    irongraphicsJuly 18, 2019
  • Banana Vanilla Protein Pancakes

    Say goodbye to frozen waffles. We’ve got your new favorite high-protein breakfast option.   In a Blender combine: 1/2 cup old...

    ironashleyApril 26, 2019
  • Fruit Trees In Urban Living

    People often look at fruit trees found in dense urban areas and assume its of offerings are nutritionally bankrupt, made up...

    Cindy MamOctober 18, 2018
  • How To Control Your Cravings

    We all have cravings right? When we are dieting, they are even more apparent. Why does our brain immediately want us...

    Cindy MamAugust 27, 2018
  • Recipe: Green Protein Drink

    The ingredients in this smoothie work together to flush environmental toxins away and cleanse the liver while providing lubrication for your...

    Cindy MamJuly 2, 2018
  • The Simple Low-Fat Pre-Workout Shake

    You want gains and you want energy. This shake will give you all that and less fat than most people’s morning...

    Sharon OrtigasSeptember 14, 2017
  • The New Rules for Macros

    Change your thinking about carbs for greater performance in and out of the gym. By Michael Schletter, CSCS*D, NSCA-CPT*D   Every...

    Sharon OrtigasSeptember 12, 2017
  • Dragon Juice

    Sweet and slightly tangy, this smoothie is low in carbs but loaded with flavor. By Amanda Burrill, MS   Meal preppers,...

    Sharon OrtigasAugust 20, 2017
  • Micronutrient Madness

    A smoothie flavor standby is kicked into overdrive with a surprise ingredient. By Amanda Burrill, MS   Are you downing the...

    Sharon OrtigasJuly 11, 2017