Casein vs. Whey: Is One Better Than The Other?

Dairy-based protein powders seem to be the evergreen choices for fitness enthusiasts. Some will tell you that Whey is best. Others swear to Casein. Casein vs. Whey is a never-ending battle.

Yet, both protein powders offer unique features. 

The following overview will cover some of the similarities and fundamental differences between the two. 

Whey and Casein: The Key Differences

Think of whey and casein like a couple of siblings – Similar but not identical in features. 

They are both milk proteins, and a glass of cows-milk will typically contain 80% Casein and 20% Whey protein. Both whey and casein contain all nine essential amino acids, making them so-called complete proteins. Additionally, they also contain a load of beneficial non-essential amino acids. 

Both Casein and Whey score 1.0, the highest possible rating, on the Protein Digestibility Corrected Amino Acid Score(PDCAAS). It is a method used to evaluate and rate the quality of a protein based on their amino acid compositions and humans ability to digest it. 

Both milk proteins are quite similar. The most notable differences between the two, however, is in the absorption rate and their composition of Branched-Chain Amino Acids.

Branched-Chain Amino Acids

Both casein and whey are rich in Branched-Chain Amino Acids(BCAAs), however, there are differences in the amounts found in each one. 

Whey is higher in leucine with about 10 grams per 100 grams of protein. This is roughly 25% more than what is found in Casein. Casein, on the other hand, is slightly higher in the other two BCAAs, namely valine, and isoleucine


  • Leucine
  • Isoleucine
  • Valine


  • Isoleucine
  • Valine
  • Leucine

These Branched-Chain Amino Acids are all believed to play important roles when it comes to building muscle, however, some more than others. 

Leucine is by far the most researched and well-known BCAA. It plays an important role in muscle protein synthesis, which is the process of building muscles. In short, muscle gain happens when muscle protein synthesis is higher than muscle protein breakdown.  

Isoleucine is believed to be important for glucose uptake, while Valine may help reduce fatigue.

Casein vs. Whey: Digestion Rate

At some point, you might have received the advice to take whey after each workout and casein before bed. In fact, it might be the most repeated phrase in the world of nutrition. This has been the hypothesis and subject of several studies, which has resulted in some interesting findings. 

One study compared the speed of digestion and amino acid absorption from casein and whey. They found that whey worked quickly and stimulated after-meal protein synthesis by 68%. Casein induced a significantly lower stimulation of 31%. 

However, unlike whey, casein also inhibited protein breakdown with 34%. Additionally, casein caused subjects to have elevated levels of leucine up to 7 hours later. Subjects consuming whey were back to their baseline levels after 4 hours.

Another study comparing fast and slow protein show similar results. Ingestion of whey protein induced aminoacidemia, a rapid and sudden influx in amino acid levels. 

Casein had a lower initial influx of amino acids, but a much more sustained release. And once more, casein ingestion caused a higher leucine balance over the span of 7 hours. 

Besides comparing casein to whey, the study also included a group consuming repeated meals of whey protein. The purpose of these repeated meals was to mimic a slow digesting protein. They found that both casein and repeated consumption of whey protein led to a better protein utilization when compared to a single ingestion of whey.

A review of the studies suggests that the digestion rate of protein is important and may be a determining factor for efficiency. Casein has proved beneficial for prolonged protein synthesis. However, whey provides a greater initial spike in protein synthesis. 

This supports the idea of taking whey protein directly after a workout, in order to fuel the protein synthesis. Casein might be better to use before bed, during a busy workday, or basically any time when there is a long pause between meals. 

The idea is to keep muscle protein synthesis going and reduce muscle protein breakdown. 

Amount of Micronutrients

Despite being derived from the same source, casein and whey contain different amounts of important micronutrients. 

Micellar Casein and Whey Concentrate are the two types of protein powder that are subject to the least amount of processing. As a result, it is these ones that contain the highest amount of nutrients. 

Both Micellar Casein and Whey Concentrate contains trace amounts of several vitamins and minerals. However, it is Calcium, Phosphorus and Magnesium that are the predominant ones. 

NutrientMicellar CaseinWhey Concentrate
Calcium2000 mg330 mg
Phosphorus1300 mg300 mg
Magnesium100 mg50 mg

Amount per 100-gram protein powder. 

Micellar Casein contains the highest amount of all three minerals and is especially rich in Calcium. One serving of a high-quality Casein Protein Powder provides an average of 600 mg, which translates to 60% of the RDA.

Casein vs. Whey: Weight Loss

Protein-rich diets have long been a popular approach to reduce weight. While a number of studies agree that protein can help reduce weight, they fail to provide any solid proof that one protein source is better than the other. 

Yet, Casein might have the upper hand when it comes to fat-burning. In a study, police officers were divided into three groups. The first group consumed protein solely from various unregulated dietary sources. The second and third groups were given whey and casein respectively. 

The results were surprising. All groups consumed the same amount of calories and lost a similar amount of weight. However, the percentage of fat loss was greatest in the casein group. Similarly, in another study that found casein and whey of equal use for increased metabolism, also found it plausible that casein was beneficial for fat loss.

From the small stack of research, it seems that Casein might have some merit when it comes to reducing fat. To increase metabolism, however, casein and whey might be equally suitable. 

Wrapping it up

It seems that both Whey and Casein has their own unique set of benefits. 

So, Casein vs. Whey: Which is best? 

Whey is high in leucine and is the most potent protein powder for increased protein synthesis. In other words, whey should be used directly after a workout. 

Casein creates a slower and longer lasting protein synthesis, in addition to reducing muscle protein breakdown. This suggests that casein should be used during fasting periods, due to its catabolic effects. Casein also creates long-lasting satiation and is a great source for Calcium. 

That said, it is unlikely that switching from one protein type to another will make or break your success. The most decisive factor is to ingest an adequate amount of protein. However, used strategically and at the right time – a combination of whey and casein might be the favorable option. 


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