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Whey vs Casein: which is the best option?

Supplementation could be an added value for different types of people, especially for those who practice exercising, in order to enhance their results.

Some of the most popular supplements are milk-protein based supplements, and these are widely used with the purpose of improving muscle recovery and enhancing the increase or maintenance of muscle mass.

Protein is the main macronutrient constituent of muscles and most organs, so it is essential to build and repair the tissues of our body.

In the case of athletes, the amount of protein consumed per kilo of weight varies from 1 to 1.5g, and in some cases it may exceed 2g per kilo of weight.

See more about the protein needs in this article.

Therefore, particular attention should be paid to the consumption of protein-rich foods such as meat, fish, dairy or eggs.

However, sometimes it may be necessary to supplement this diet with supplementation so that we can respond to the needs of our bodies in an easier, more efficient and pure way.

Within this category of supplementation, the most common supplements to which athletes resort are whey or casein.

Studies reveal that:

“(…) ingestion of casein and whey proteins after resistance exercise stimulated net muscle protein synthesis by providing essential amino acids. Thus, consumption of whole proteins after exercise may be an effective strategy to increase muscle size and strength.”

But often doubts arise about choosing between whey and casein and when to take. What are the main differences between the two? What’s the best option for you?

See the answer to these and other questions in this article!

Whey vs Casein?

whey vs casein

Whey represents 20% of the cow’s milk protein and casein the remaining 80%.

Whey protein is one of the golden ingredients for an athlete because it is a protein of high biological value and therefore has very interesting effects when supplemented before and/or after training.

Whey has a high biological value (104) because it is a protein easily and quickly absorbed and used by the body.

Biological value: “the nutritional effectiveness of the protein in a given food, expressed as the percentage used by the body of either the total protein consumed or the digestible protein available.”

In this article, you can understand better the biological value issue.

On the other hand, casein has a lower biological value than whey protein (70).

Both whey and casein are complete proteins, which means that they contain adequate quantities of all essential amino acids (as BCAA’s), those that our body does not produce and which must be acquired through food or supplementation.

The whey that is marketed can be divided according to its composition and can be generally divided into three types, whey concentrate, whey isolate and hydrolyzed whey.

  • Concentrate: It is the most popular and most consumed, it has between 70 to 80% of protein, being the content remaining carbohydrates and fat.
  • Isolate: It is a purer form of consuming this type of protein, having approximately 90/95% protein, being virtually free of sugars and fat.
  • Hydrolyzed: It is “deconstructed”/broken into smaller portions, something that will facilitate the absorption by the body.

See more about each of these types here.

Therefore, the key characteristic of this protein is its easy and fast absorption by the human body, so the amino acids will be more readily available in large quantities so that our body immediately uses them to recover and rebuild.

Whey protein is considered a anabolic protein (which promotes muscle construction).

You can get to know more about this type of protein in this article.

On the other hand, the digestion time of the casein is about twice the time of digestion of the whey protein, and one of the reasons pointed to this is the higher size of its molecules and the fact that, once in the stomach, it forms a kind of gel.

According to an article published in the “Journal of Sports Science & Medicine” about the comparation between whey and casein:

“Casein is water insoluble and coagulates, resulting in a slow-release mechanism of amino acids that is sustained at increased levels in the body for a longer period of time.”

Casein is then considered a slow absorption protein and thus prevents or decreases muscle catabolism during periods of fasting, therefore, its consumption is usually indicated for the period before bedtime.

What is the best option: whey or casein?

Knowing that both have benefits at the level of construction and maintenance of muscle mass, the question should be put as:

When should I consume casein or whey?


Casein and whey can be taken at the same time or at different times. That depends on the athlete in question and his goal.



It shows itself very important in muscle maintenance, so as to avoid loss in muscle mass induced by periods of higher food fasting.

For athletes who will endure long periods of fasting, it will make more sense to consume in the hours preceding the casein, since the digestion of this will be slower and will prevent the muscle from being “spent”.

The athlete will also feel more energy throughout that period.



The consumption of whey may vary within the type of whey consumed. As I mentioned, there are three main types of whey.

Whey concentrate is best suited for those looking to increase muscle mass without weight worries, and to speed up muscle recovery.

The whey isolate will make more sense to be consumed by those seeking to achieve some muscle definition without increased weight, since it has practically 0 sugars and fats.

Note: It can also be an option for people who have some lactose intolerance because they have a reduced amount of lactose.

The hydrolyzed whey is a whey that is more easily digested, being ideal for those who feel a greater discomfort by taking the others.

As it is quickly digested and absorbed, the moments of consumption may be before and/or after training and it will depend on the individuality of the athlete.

In conclusion…

Casein and whey, in a way, may complement each other, since they are advised in an individualized manner to enhance the results of the athlete.

It is not possible to highlight one of them because, although they have some differences, they have the same purpose: improved performance and muscle recovery and the increase or maintenance of muscle mass.

The choice can be made taking into consideration the need of the person: whether they want more immediate support or more prolonged support, since the main difference is the speed of absorption and digestion.

There are those who choose to consume both types, for example at the moment workout. Thus, they will benefit from both speeds, and the release of amino acids is fast and sustained at the same time.

See what works best for you and ask a professional for help if you have any questions.


The information included in this article concerns the authors opinion only.

About Ângela Ferreira

Ângela Ferreira
Ângela Ferreira is a nutritionist. She has a degree in Nutrition Sciences and she is doing a Master's degree in Consumer Sciences and Nutrition. She currently works in Sports Nutrition and Clinic Nutrition. Her goal is to actively participate in changing the population's eating habits and to demonstrate that healthy eating can be simple and practical.

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