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The Best Type of Protein to Build Muscle

building muscle

Because protein is necessary to build muscle, many bodybuilders and other athletes supplement their protein intake with protein supplements. Using protein powders is a great way of increasing your protein intake without having to consume too many extra calories.

The proteins found in protein powders and supplements generally come from one of these three sources:

Whey - from milk
Casein - from milk
Soy - from soy beans

Whey and Casein Protein

Because both whey and casein are found in dairy milk they are proteins that are consumed by many people everyday. The protein in milk consists of 80% casein and 20% whey (Snyder and Haub, 2007). Ingestion of both casein and whey protein have been shown to increase muscle synthesis after exercise (Tipton et al. 2004). In addition, just drinking milk after a workout has been shown to increase protein synthesis (Elliot et al., 2006). This makes sense because milk contains both casein and whey protein but in lesser amounts than what you would get in a protein supplement.

Which Type of Protein Powder is Best?

Whey Protein

Whey protein contains the highest number of branched chain amino acids (BCAAs). The BCAAs consist of leucine, valine, and isoleucine. The BCAAs are digested more quickly than the proteins found in casein and so the BCAAs are available as an energy source or for protein synthesis very quickly after ingestion. Drinking whey protein before a workout will provide your muscles will energy during your workout. Some athletes prefer to feed their muscles immediately after a workout and so they drink their whey protein as soon as they are done working out, and some athletes drink their whey protein both before and after their workout.

In addition, whey protein contains all 20 amino acids and also consists of individual proteins that provide health benefits and support for athletes. There are several different brands and flavors available and they all taste best if they are mixed with milk instead of water and if you use a blender or shaker cup to mix them. This is true not only of whey, but for all types of protein powders.

The source of most whey protein powders is cow's milk, but there is one company that sells whey protein from goat's milk. Absorption of goat whey is supposed to be greater than with whey derived from cow's milk. I found that the taste of goat whey was not as good as whey from cow's milk.

Casein Protein

Casein is digested more slowly than whey and so it takes the amino acids longer to get into the bloodstream (Synder and Haub, 2007). So, if you are looking for a protein that digests slowly, then you want casein. Although the absorption rate is different for whey and casein protein, research studies have shown that they both increase protein synthesis of muscle after exercising (Synder and Haub, 2007).

However, a study by Demling and DeSanti (2000) examined the effects on overweight police officers who took protein supplements (casein hydrolysate or whey hydrolysate) combined with resistance training and a reduced calorie diet. After 12 weeks they found that the casein group (n = 14) lost more fat and gained more strength in the chest, shoulders, and legs than the whey group (n = 14) did. From the results of this study it seems that if you are looking to build lean muscle mass then casein may be the best protein supplement for you.

In addition, some people use protein powders to supplement their daily protein needs. If you are using a protein shake as a meal replacement (for breakfast for example) then casein might be best because it is digested more slowly. If you drink a whey shake to replace a meal then you may end up feeling hungry much earlier than if you drink casein.

Soy Protein

Some athletes may prefer a vegetarian source of protein. Like whey protein, soy protein is digested and absorbed rapidly. Research studies have shown that ingestion of soy protein does increase lean muscle mass, but not as much as milk derived sources of protein.

In general, plant derived proteins are not as biologically active as animal sources of protein. For example, Wilkinson et al. (2007) conducted a study in which they tested whether soy or milk beverages would increase protein synthesis most after resistance exercise in men. They found that both soy and milk proteins increased protein synthesis, but that protein synthesis was greater after drinking milk protein than soy.

Also, milk proteins contain immunoglobulins which provide health benefits that you won't find in soy. However, soy proteins contain isoflavones and phytoestrogens which also provide health benefits.


It seems that whey protein is best immediately before and after a workout, but that casein is best at other times. Soy, while providing some increased muscle synthesis, will not help you build as much muscle as either whey or casein. However, if for some reason you are unable to drink milk proteins due to an allergy, or if you are a vegetarian who does not drink milk or milk products then soy will be a good protein source. In research studies soy does increase protein synthesis, but not to the extent that milk proteins do.

Some athletes choose to vary their protein sources throughout the day. If you want to feed your muscles immediately before or after a workout then they have a whey protein shake. Often, they will drink a casein shake before going to bed. In this way they have a steady supply of energy during their workout, and a steady flow of amino acids in their bloodstream during the night to aid in protein synthesis.

Keep in mind that simply drinking protein shakes won't help you build muscle unless you work out. Also, any protein you intake that is not used to build muscle or used for other bodily functions will simply be used as an energy source and excess protein is excreted by the kidneys.

A word of caution - people who have existing kidney problems should check with their physician before taking protein supplements because there is some evidence that high protein intake may exacerbate the problem.


Demling, R.H. and DeSanti, L. (2000). Effect of hypocaloric diet, increased protein intake and resistance training on lean mass gains and fat mass loss in overweight police officers. Annals of Nutrition and Metabolism 44, 21-29. 83: 355-361.

Elliot, T.A., Cree, M.G., Sanford, A.P., Wolfe, R.R., and Tipton, K.D. (2006). Milk ingestion stimulates net muscle protein synthesis following resistence exercise. Medicine and Science in Sports and Exercise 38, 667-674. 83: 355-361.

Snyder, B.S. and Haub, M.D.(2007). Whey, casein, and soy proteins. In Judy A. Driskell (Ed.), Sports Nutrition: Fats and Proteins, pp. 143-163, Boca Raton, FL: Taylor and Francis Group.

Tipton, K.D., Elliot, T.A., Cree, M.G., Wolfe, S.E., Sanford, A.P., and Wolfe, R.R.(2004). Ingestion of casein and whey proteins results in muscle anabolism after resistance exercise. Medicine and Science in Sports and Exercise 36, 2073-2081. 83: 355-361.

Wilkinson, S.B., Tarnopolsky, M.A., McDonald, M.J., McDonald, J.R., Armstrong, D., and Phillips, S.M.(2007). Consumption of fluid skim milk promotes greater muscle protein accretion after resistance exercise than does consumption of an isonitrogenous and isoenergetic soy-protein beverage. The American Journal of Clinical Nutrition 85, 1031-1040. 83: 355-361.