Why Whey Protein Is The Best Choice For Building Muscle

Whey Protein

Optimum Nutrition Gold Standard Whey Protein

There are a few reasons why whey protein is optimal for building muscle over any other protein source including casein, soy, brown rice, collagen, etc. Please understand that I am not trying to tell you to never eat those sources, I am just trying to inform you of what’s proven and what good marketing can make you believe. If your looking to build lean muscle, then whey is the way to go. You may find a cheap protein brand on sale that may seem like a good deal, but if you look at the active ingredients, you will find that many contain cheap fillers like casein and collagen protein as well as other strange ingredients like corn syrup solids (gross). I recommend just whey protein. I’m sure that we have all been told to have casein protein at night because it’s slow digesting and will prevent us from losing precious muscle while we sleep (lol). While this is a good idea, I’d rather tell you what’s optimal for muscle protein synthesis. The reasons why whey is the way are as follows:

1) It’s leucine content

2) It’s ability to increase muscle protein synthesis more effectively at rest AND post exercise

Now you may be wondering what the heck is leucine but it is one of three branched chain amino acids and a key factor in stimulating muscle protein synthesis (production). The amount of leucine required to ingest is also of significance as muscle protein synthesis has been shown to have a minimum threshold and maximal rate1. This max value varies depending on an individual’s size but can range from about 3-4 grams. Every protein source contains amino acids and depending on the protein source, the amount of leucine will vary.

Leucine and Total Amino Acid Content Of Various Protein Sources




Leucine (G)




Total (G)




Data Source2

Whey protein has also been shown to increase muscle protein synthesis both at rest and post exercise to higher levels than both casein and soy2. So in terms of muscle protein synthesis, the post workout “anabolic window” does appear valid. So by looking at the table above, I suggest consuming about 35-40 grams of whey protein post workout in order to optimally stimulate muscle protein synthesis (more protein≠higher rate of synthesis). I also suggest consuming this protein along with a carbohydrate source as the spike in insulin maintains cellular energy status. Along with leucine, this signals translation initiation, a critical step for muscle protein synthesis3.

Mixed muscle protein fractional synthetic rate (FSR).
Mixed Muscle Protein Fractional Synthetic Rate (FSR). Source2

In summary, whey protein is the best option in terms of building muscle. Is it the only way? No; there is nothing wrong with the other sources of protein but they are not optimal. So don’t allow the supplement industry to make you believe that you will lose all your muscle overnight because you didn’t have your casein shake. Hit your targeted calories and macronutrients daily and take advantage of your body’s ability to increase muscle protein synthesis post workout as shown in the image above.Lastly, I would like to thank everyone involved in the studies shown below who put in the effort to bring us the latest data available.



1) Norton LE, Layman DK, Bunpo P, Anthony TG, Brana DV, Garlick PJ. The leucine content of a complete meal directs peak activation but not duration of skeletal muscle protein synthesis and mammalian target of rapamycin signaling in rats. J Nutr. 2009 Jun;139(6):1103-9.
2) Tang JE, Moore DR, Kujbida GW, Tarnopolsky MA, Phillips SM. 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. 2009 Sep;107(3):987-92.
3) Wilson GJ, Layman DK, Moulton CJ, Norton LE, Anthony TG, Proud CG, Rupassara SI, Garlick PJ. Leucine or carbohydrate supplementation reduces AMPK and eEF2 phosphorylation and extends postprandial muscle protein synthesis in rats. Am J Physiol Endocrinol Metab. 2011 Dec;301(6):E1236-42.