The Case Against Casein vs. Whey Protein Powder

casein vs. wheyAre you wondering which protein supplement to get? Casein vs. whey. This is a common question in the strength and fitness world.

The two proteins have a lot in common. They come from the same source and they’re both full of good amino acids. These compounds are what makes you stronger.

Are they more or less the same?

The answer is no. The two dietary proteins differ in a couple of ways and will affect your body in different ways.

So, which is better and why?

There’s been some controversy and confusion around that topic. But this article will teach you which one is superior, and how and why.

What Are Casein and Whey?

Both are dairy proteins. They naturally occur in milk. Casein is what forms the curds in cottage cheese and other fresh cheese. Whey is the liquid that surrounds it, and is typically removed from cheese.

Proteins supply your body with the amino acids it needs to build and repair tissue. In other words, they’re what makes your muscles grow.

Dietary proteins aren’t all equal though. Many are incomplete, especially the ones found in plants. Both whey and casein are superb sources of all essential amino acids. But they differ in other ways.

Casein takes a long time to digest, just like most protein found in food. When, on the other hand, can be absorbed in one to four hours.

This makes their roles as muscle building supplements quite different.

Casein Protein

Around 80 percent of the protein found in milk is casein. This protein is known for its slow digestion and anti-catabolic properties.


Casein clots in the stomach, making it digest at a slow rate. This seems to make it anti-catabolic.

The calcium content can help with muscle and bone health, as well as body composition.

Slow digestion can keep you full longer when you’re cutting weight.


The slow digestion rate makes it a poor choice for pre- and post-workout protein supplementation. You want a quick addition of amino acids, not a digestive struggle that wastes your energy.

Comparing casein vs. whey for workout boosters, casein isn’t as good.

Some are allergic, and others may feel their lactose intolerance triggered. This leads to gas and bloating. Not to mention lowered energy and strength.

The sodium levels can also cause bloating. The water retention from sodium can pose a problem if you need to weigh in for a competition.


If you have no adverse effects from casein, it makes a nice supplement for your meals.

It’s not a good choice in the gym when you’re trying to accelerate absorption of amino acids.

Whey Protein

Whey is the natural byproduct of making cheese. Whey protein constitutes about 20 percent of milk protein.


Whey contains high levels of branched-chain amino acids (BCAA). Studies confirm whey protein’s ability to increase protein synthesis.

It’s also rich in vitamins and minerals. It contains lactalbumin, which resembles serum albumin. There’s also a little bit of lactose and fat.

Whey boosts glutathione levels. This tri-peptide of cysteine, glycine, and glutamic acid is an important part of plant and animal tissue. It defends against oxidative damage.

Glutathione helps keep molecules like iron in the right oxidation state in your hemoglobin. The high cysteine levels of whey contribute to ensuring whole blood glutathione.

This makes whey good for your immune function. It also reduces the oxidative breakdown of muscle.


In a comparison of casein vs. whey, casein brings a greater reduction of protein breakdown.


The fast digestion rate makes it readily available at all times. It’s perfect for a pre- or post-workout protein boost. You’ll have more energy rather than less.

Due to the BCAA content, it can help even during your workout.

Casein vs. Whey

People often ask which milk protein is better.

They work in different ways, and some consider them supplements for separate purposes.

That’s not to say you can’t do a direct comparison. Let’s look at how they compare.

Case Study

In this study, subjects were given 30 grams of either whey or casein protein after a ten hour fast.

Blood leucine levels peaked within an hour of consumption of casein or whey. The whey subjects all had higher peaks though, and took four hours to baseline. Casein caused a lesser leucine peak and took seven hours to baseline.

Whey protein boosted postprandial protein synthesis by 68 percent. Casein did not do the same but inhibited protein breakdown by 34 percent.

The study showcases the benefits and differences of the two proteins. It’s important to note that mixed protein meals would digest at a different rate. This might alter the impact on protein synthesis and catabolism.

But the answer is quite clear. When it comes to casein vs. whey, whey is the winner.

Protein Sources

Both proteins occur naturally in milk and most dairy products. Cheese contains casein but no whey. The exception is ricotta cheese, which is made from whey only. Certain fish also contain casein.

Casein is sold in its micellar form. It’s more or less unadulterated, it’s just filtered. Its structure is still intact.

The purest type of whey protein is whey protein isolate. It contains about 90 percent whey protein and not much else.

Whey protein concentrate contains between 29 and 89 percent whey protein. Look closely to ensure high protein content. The lower the protein content, the higher the fat and lactose content.

Both when and casein also come in hydrolyzed form. The protein in these products is already broken down into peptides to aid amino acid absorption.

The Best Choice?

The faster digestion rate of whey makes it pass through your stomach faster. This means you get a quick, big surge of plasma amino acids. This results in a quick protein synthesis increase.

Casein takes much longer and doesn’t have a big impact on protein synthesis. Whey contains more leucine, a powerful amino acid which stimulates muscle growth.

Whey protein is the superior choice for boosting protein synthesis. Repeated use throughout the day keeps your serum amino acid level high and makes your muscles stronger.

Many consider the two proteins complementary and keep a stock of both. Another popular combination is mixing the whey protein into milk.

Choose Whey Protein

There you have it, a comprehensive comparison of casein vs. whey protein.

Whey is your best friend when you want to build more muscle in less time. There are many different kinds and qualities of whey supplements out there.

Learn more about nutrition and supplements today!

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