What is whey protein?

whey protein

What is whey protein?

Whey Protein

Over the years, whey has become the goto protein for athletes, dieters, and fitness enthusiasts. This series will focus on whey and its ability to deliver on a assortment of claims. We’ll discuss whether whey helps with performance, weight loss, muscle building, recovery, and more!


Proteins 101

Amino acids are the building blocks of all tissue in the body. Proteins are simply a chain of of amino acids linked together. In all, there are 21 amino acids the body needs. Proteins differ from one another based on both the amino acids they contain, as well as the order those amino acids are linked in. When you change the type or order of amino acids, you get a new protein that behaves differently in the body1.

Proteins are all unique. If we compare whey to casein, proteins derived from milk, we see some significant differences; mainly digestion and absorption time. Both of these proteins come from milk, but are very different in the way they behave.

Short History of Whey Protein

Whey is a byproduct of cheese production, and for a long time, was considered a waste product. This is a far cry from its status today as king of all supplements. In the “old days”, cheese production was done on a small scale. Whey was either fed to animals, discarded in rivers and lakes as waste, or used in making limited food products2.

As cheese production increased, so did the concern over dumping and discarding large amounts of whey. In some areas, local authorities began placing limits on how much dairy waste could be dumped per day. This drove the need to find other uses for whey2.

Whey is made of only 6.5% solids; the rest is liquid. Turning this liquid into a dry powder takes considerable effort. Over the decades, we’ve seen tremendous technological advancements making this transformation possible and efficient2.

Whey began its retail journey in the late 1980s when an Olympic athlete named David Jenkins started marketing it for its potential in aiding the recovery process. From there, whey protein evolved as new and better methods of producing it were refined. In the 1960s whey was sold as pig feed for about $250 per metric ton; today, we’re spending $10-$20 per pound2!

What is whey protein?

Milk is made up of two different proteins: whey and casein. To make cheese, bacteria and enzymes are added to milk causing the casein curdle. The casein is removed, and the thin, watery liquid that’s left behind is whey. This is further processed, and eventually becomes a powdered protein supplement2.

Whey is a broad term. Today, there are three main forms of it: whey powder, whey concentrate, and whey isolate. Processing removes water, lactose, and some minerals to increase protein content. Whey concentrate is 25-89% protein while whey isolate is 90% or more protein2.

Whey Protein Quality

Simply looking at the amount of protein found in a supplement is sometimes not enough. Proteins can vary in quality based on a few factors and are graded on their amino acid content, digestibility, and bioavailability. There are a few methods we use to grade proteins.

Protein Efficiency Ratio

One way to measure the quality of a protein is to determine how much growth it causes. In this method, researchers feed protein to a rat. They compare the amount of weight gain to the amount of protein it consumed. The standard value is 2.7 (which is the protein efficiency ratio of casein protein). Anything above 2.7 is considered excellent. The protein efficiency ratio of whey is 3.23.

Biological Value

Protein is unique because it contains nitrogen; an element necessary for tissue growth. This method generates a ratio: how much of a protein’s nitrogen was used for growth compared to how much nitrogen was consumed from a food. A score of 100 means that 100% of nitrogen consumed was used for tissue growth. The biological value of whey is 104 (scores greater than 100 are typically caused by inaccuracies in measurements). Scores approaching 100 indicate a high quality protein3.

Protein Digestibility Corrected Amino Acid Score (PDCAAS)

This tool measures a protein’s amino acid quality. It compares the amount of essential amino acids the body uses from the test protein to a reference protein. A value of 1.0 is the highest (best) score. The PDCAAS of whey is 1.0, indicating it is a high quality protein3.

The Bottom Line

Whey protein is a popular and low cost way of increasing protein intake. Based on three different tests, whey appears to be a very high quality protein in terms of its amino acid composition and ability to grow tissue. In this series, we’ll take a closer look at whey’s ability to deliver on specific goals and conclude with a recommendation on whether or not it is worth including in your supplement regimen.

Whey Protein Series

Is whey protein safe?

Way too Many Types of Whey Protein

What type of whey protein works best: concentrate, isolate, or hydrolysate?

Does whey protein build muscle?

Does whey protein decrease muscle soreness and muscle damage? (coming soon)

Does whey protein improve recovery? (coming soon)

Does whey protein increase strength? (coming soon)

Does whey protein help with weight loss? (coming soon)

Does whey protein lower body fat percentage? (coming soon)

Does whey protein help with cardio? (coming soon)

Is whey protein worth taking? (coming soon)


  1. Martos, M., & Turnbough, M. (2012, June 28). Protein Parts. Retrieved from https://askabiologist.asu.edu/venom/building-blocks-protein.
  2. Deeth, H., & Bansal, N. (2019). Whey proteins: from milk to medicine. London: Academic Press. doi: 10.1016/B978-0-12-812124-5.00002-3
  3. Hoffman, J. R., & Falvo, M. J. (2004). Protein – Which is Best? Journal of Sports Science and Medicine.