Casein vs. Whey: Which Protein Powder is Right for You?

Casein vs. whey: the battle of the proteins. Which one is the best option for your fitness goals? Find out in this article!

Casein and whey protein are the two major proteins of milk. Both are high-quality proteins that provide all the essential amino acids the human body requires and are popular as protein supplements among bodybuilders and fitness enthusiasts.

They are similar in many ways but have significant differences and unique benefits.

casein vs. whey from milk
Both casein and whey are milk proteins.

In this article, we’ll explore the differences between casein and whey protein and help you determine the best option for you, whether you’re looking to build muscle, lose weight, or improve your overall health and fitness.

What Is Protein Powder?

Protein powders are dietary supplements that contain high levels of protein extracted from sources like milk, soy, egg, rice, pea, and hemp.

They are traditionally used by athletes, bodybuilders, and fitness enthusiasts to boost muscle growth, recovery, and muscle repair.

In essence, protein supplements are high-protein food in powder form.

During the last decades, protein powders have become increasingly popular outside of the fitness community, and many people use them to help with weight loss and overall health and wellness.

Back in the day, you could never really be sure if the tub of protein powder you just bought actually contained what it said on the nutrition labels. It often dissolved like wallpaper paste and tasted, at best, like sawdust.

These days, you can easily find many different types of proteins with a tremendous amount of variety: everything from casein and whey to plant-based protein powders like pea and soy protein. Protein powders are widely available and come in various flavors and forms. 

Why Is Protein Important?

Protein is an essential nutrient that plays many crucial roles in your body. The protein you eat provides the building blocks for almost all tissues in your body, like your organs and skin, not to mention your muscles.

In addition, protein supports numerous vital bodily functions like the production of enzymes and hormones, maintaining your immune system, and the transportation of nutrients throughout your body.

casein vs. whey functions of protein

In sports nutrition, protein is vital for muscle protein synthesis, repair, and recovery. Eating enough protein is crucial for improving performance and building muscle. If you get too little, you’ll find it challenging to get the results you want

Protein also makes you feel full for longer, aiding in weight management.

Casein vs. Whey: A Brief Overview

Casein and whey are the two main types of protein in cow’s milk. Whey is a by-product of cheese production, while casein is directly derived from milk. Both are separated, processed, and sold as powders for use in dietary supplements.

casein vs. whey how they are made

Casein Overview

  • Casein protein is a so-called “slow protein,” meaning it takes longer to break down in the body and release amino acids compared to whey protein.
  • It can sustain muscle protein synthesis for a long time and is often marketed as a “night protein” as it provides a steady release of amino acids throughout the night.
  • Casein is a high-quality protein with an excellent amino acid profile and is considered to be highly nutritious. The two main types of casein protein powder are micellar casein and calcium caseinate, with the former being the slowest-digesting option.
casein vs. whey: casein protein
Casein is the primary protein in most dairy products.

Whey Overview

  • Whey is a fast-digesting protein that is rapidly absorbed, increasing the amino acid levels in your blood faster than any other protein.
  • It is particularly rich in branched-chain amino acids (BCAAs), often used for post-workout recovery due to its effectiveness in boosting muscle protein synthesis.
  • The two main types of whey protein powder are whey protein concentrate and whey protein isolate. The main difference between the two is that isolate contains less fat and milk sugar, making it suitable even if you’re lactose intolerant.

Read more:

>> Whey Protein Concentrate vs. Isolate: What’s The Difference?

casein vs. whey: whey protein
You can’t get isolated whey protein from regular foods, making protein powder the go-to solution.

The absorption of dairy proteins is 5–6% more complete than other proteins in general, making both casein and whey ideal for muscle growth and athletic purposes.1

Casein Protein Powder: Benefits and How To Use It

Casein is a type of protein you find in milk and other dairy products like cottage cheese. In regular cow’s milk, 80% of the protein is casein, while the remaining 20% is whey.

Like other animal proteins, casein contains abundant amounts of all the essential amino acids, making it a complete protein source for your body’s needs.

Casein digests slowly and forms a blob in your stomach after you ingest it, slowing absorption down over several hours.

Read more:

>> Casein: Fast Gains from Slow Protein?

Benefits of Casein Protein Powder

Casein protein has several unique benefits, mainly due to its slow release of amino acids.

Sustained Release of Amino Acids

Casein does not stimulate muscle protein synthesis as rapidly and robustly as whey. Instead, it keeps it moderately elevated for a long time, making casein protein supplements ideal for when you go a long time without eating, like overnight while sleeping.

Appetite Control

A high protein intake can help manage your appetite and control your food intake by promoting feelings of fullness and reducing hunger.

Research suggests that whey protein provides greater short-term feelings of satiety, while casein is more satiating in the long term.2

In other words, if you have hours without food ahead of you, a shake with casein protein powder can be a good idea to stave off hunger.


Casein protein shakes are a convenient and easy way to increase your overall protein intake when you don’t have time to prepare and sit down for a complete meal. 

Because casein is rich in all the essential amino acids needed for muscle growth and repair, it’s a great option for athletes and bodybuilders looking to maintain or build lean muscle mass.

Health Benefits

In addition to being one of the best protein sources for muscle gain, casein supplements might benefit your health by helping reduce blood pressure.3

Casein is also rich in calcium and phosphorus, which are essential for maintaining healthy bones and teeth.

How to Use Casein Supplements

Casein is a versatile protein that you can use to boost your protein intake in many scenarios.

General Protein Supplementation

You can use casein protein powder as a general protein supplement to increase the protein content of your diet to support your overall health and reach your fitness goals.

You don’t have to treat casein protein with more respect than any other protein from whole foods. Simply count it towards your daily protein intake.

Bedtime Snack

Because of its slow-release properties, many bodybuilders and fitness enthusiasts use casein protein powder as a nighttime snack before bed to elevate muscle synthesis throughout the night.

There is no definite evidence that doing so leads to more significant muscle gain than consuming the same amount of protein at another time. However, it’s an easy way to ensure your muscles have access to a steady supply of amino acids while sleeping.4

You could eat a protein-rich meal before going to bed, but to get the necessary amount of protein, you need to eat seven eggs, two steaks, or two chicken breasts.5 That amount of food right before bed might keep you awake for hours, which is not ideal for muscle growth and recovery, while a protein shake is more easily digested.

Weight Loss

Protein supplements do not make you lose weight, but casein protein powder can help you feel full, control your appetite, and reduce snacking between meals, making it an effective supplement for fat loss and weight management.

Extended Periods of Fasting

When you know you won’t be able to sit down for a meal for many hours, drinking a casein protein shake is one of the best ways to ensure your body has access to the building blocks it needs.

Due to its slow digestion, it keeps you full for longer. It provides your muscles with amino acids during extended periods without food, such as intermittent fasting or during long times between meals.

Post-Exercise Recovery

Rapidly digested whey protein would be superior after a workout, right? 

Not so fast. 

Research shows that your muscles are more sensitive to amino acids at this time, making casein a viable option to enhance muscle protein synthesis and muscle recovery after a training session.6

Whey Protein Powder: Benefits and How To Use It

Like casein, whey protein is a milk protein: cow’s milk contains 20 percent whey and 80 percent casein. Unlike casein protein, whey is rapidly absorbed and floods your bloodstream with amino acids shortly after ingestion.

Whey protein is particularly rich in leucine and other important amino acids for building muscle tissue.

It is more effective for boosting muscle protein than casein and plant-based protein powders like soy and is often used by athletes and fitness enthusiasts to promote muscle growth and repair.

whey vs casein vs soy protein

While short-term muscle protein synthesis does not necessarily translate into greater muscle growth over time, a 2019 review concluded that whey protein supplementation is a “valid nutritional strategy for maximizing muscle mass gain.”7

The two most common types of whey protein are whey concentrate and whey isolate. Both are equally effective for building muscle. Isolate is more highly refined, with most of the milk sugar removed, making it suitable even for those with lactose intolerance.

Read more:

>> Whey Protein: The Complete Guide

Benefits of Whey Protein Powder

Whey protein supplements are highly versatile and offer many benefits for muscle gain and health.

Promotes Muscle Growth

Whey protein has a very high amino acid content and is especially rich in branched-chain amino acids (BCAAs), which are important for muscle protein synthesis. Consuming whey protein before or after exercise is a simple but effective strategy to enhance muscle hypertrophy.

Improves Strength

Regular consumption of whey protein can improve strength, especially when combined with resistance training, perhaps better than other proteins.8

Helps with Weight Loss

Whey protein can help with weight loss by promoting feelings of fullness and reducing calorie intake. A whey protein shake or two on a daily basis improves your body composition and increases muscle gain and fat loss when used as a replacement for other calorie sources.9

Health Benefits

Whey protein has several positive health effects due to its rich amino acid profile, bioavailability, and ease of digestion. For example, it supports your immune system, combats high blood pressure, acts as an antioxidant, and improves blood sugar control.10 11

Ideal for Older Adults

As we age, our muscles don’t respond to protein intake as they used to. Research shows that rapidly digested protein, like whey, is superior for boosting muscle protein synthesis in older adults and can help preserve muscle mass and function, which can decline with age.12

How to Use Whey Protein Supplements

Like other protein supplements, whey protein is food in powdered form. That means you can use it like you would any other high-protein food in your diet: as a snack, as a main protein in a meal, before or after a workout, or at any additional time of the day to boost your overall protein intake.

Here are some suggestions on how and when to use whey protein.

General Protein Supplementation

Like casein, whey protein is an excellent choice to increase your daily protein intake, especially if you struggle to consume enough protein through whole foods alone. It’s both convenient and cost-effective compared to many other high-protein foods.

For example, you can add a protein shake between main meals or turn your morning meal into a protein bomb by mixing some whey powder into your breakfast oatmeal.


The most popular time to drink a whey protein shake is after working out. Your body needs protein after a resistance exercise session to kickstart muscle protein synthesis, and a fast-acting protein like whey is ideal for quickly delivering amino acids to your muscles.13

A protein shake is a convenient way to ensure proper post-workout nutrition.


Consuming whey protein before your workout is just as effective as chugging a shake afterward. Your muscles can use those amino acids to build muscle once you’re done lifting.14

As a Snack or Meal Replacement

Whey protein can be used as a mid-morning or mid-afternoon snack to help stave off hunger and give your muscles a steady supply of building blocks. A scoop of whey mixed in water is a super-convenient and quick snack that enables you to reach your daily protein goals.

As a Bedtime Snack

Some studies suggest that consuming a slow-digesting protein like casein before bed can promote muscle recovery and growth overnight. However, you can also use whey protein as a pre-bedtime snack. A recent study found no differences in overnight muscle synthesis between the two types of protein.15

Casein vs. Whey Protein Powders: Main Differences

While both casein and whey protein are derived from milk and are complete proteins, the two have several key differences. 

Digestion Rate

The main difference between casein and whey protein powders is their digestion rate.

Whey protein is a fast-digesting protein that is quickly absorbed by the body. After consuming whey protein, your muscle protein synthesis spikes dramatically but returns to baseline after only a couple of hours.

In contrast, casein protein is a slow-digesting protein that provides a steady stream of amino acids over time. Casein does not boost muscle protein synthesis like whey but keeps it moderately elevated for hours.

  • In theory, whey protein is ideal for post-workout recovery, and casein protein is better for promoting muscle growth and recovery during extended periods without food, like when you fast overnight.
  • In practice, it doesn’t seem to matter much what, if any, protein powder you use as long as your total protein intake is sufficient.

For older adults over 50, whey protein is the superior choice. Older muscle responds better to rapidly digested protein.16

Amino Acid Profile

Both casein and whey protein are considered high-quality, complete sources of protein. They contain all the essential amino acids required by your body for health and muscle building.

However, the ratio of amino acids in each protein differs. 

Whey protein is particularly rich in branched-chain amino acids (BCAAs), which are crucial for muscle growth and recovery. In particular, the branched-chain amino acid leucine tells your body to kickstart muscle protein synthesis.

Read more:

>> BCAA Supplements: Benefits and Side Effects

Casein protein contains BCAAs, but in lower amounts than whey protein, meaning you have to consume more of it for a meaningful impact on muscle protein synthesis. On the other hand, casein contains a higher proportion of the amino acid glutamine, which is important for immune function and gut health.

Taste and Texture

Most people generally find whey protein more palatable than casein protein, with a smoother texture and a more neutral taste. 

Casein protein powders have a thicker, more pudding-like texture when mixed with water or milk but don’t dissolve as well and can get a little lumpy.

Casein vs. Whey Protein: Dosage

You want around 3 grams of the amino acid leucine per serving for a substantial muscle-building effect.17

  • Whey contains very high amounts of leucine, and 25 grams of whey protein gives you enough leucine to maximize muscle protein synthesis. The exception is after a full-body workout when your muscles are more sensitive. Then you can use 40 grams for an additional muscle-building effect.
  • Casein is higher in leucine than many other proteins but significantly lower than whey protein. That means you need more of it to reach the so-called “leucine threshold.” A 35–gram serving provides the 3 grams of leucine you’re after.
casein vs whey 40 grams

However, research suggests you should be open to exceeding average protein intake recommendations if you want to build muscle.

Consuming 0.4–0.55 g/kg/meal ensures you get enough to maximize the immediate muscle-building effects and make reaching your daily protein goal for long-term gains easier.

That goes for any protein source in your diet, including protein supplements.18

If you know you’re not getting another meal for an extended time, like before bed, at least 40 grams of protein is likely a good idea. Pre-sleep casein is the option most backed by research.

There is no set upper limit on how much casein or whey protein you should consume daily. A varied diet where you drink 1–3 casein or whey protein shakes (containing ≥30 grams of protein each) per day is typical among bodybuilders and fitness enthusiasts, in addition to the protein you obtain from food sources such as meat, fish, eggs, and legumes.

Of course, you don’t need a single shake if you prefer to get your daily protein from regular foods.

Remember that 40 grams of protein do not mean 40 grams of protein powder. No protein powder is 100% pure protein. If your whey or casein powder contains 80 grams of protein per 100 grams, you’d need 50 grams of powder to get 40 grams of protein.

Casein vs. Whey: Lactose Content

Lactose intolerance is the inability to properly digest milk sugars, resulting in uncomfortable symptoms like gas, bloating, nausea, and diarrhea.

Because casein and whey are derived from milk, they naturally contain some lactose, whey more so than casein. That can be an issue; you don’t want to rush to the bathroom whenever you chug a protein shake.

Even if you are lactose intolerant, using whey isolate is usually possible with little risk of discomfort. Almost all of the lactose in whey is removed while making the protein powder.

Many casein and whey protein powders also have added lactase enzymes, making them viable even if you are lactose intolerant.

If you still can’t find a casein or whey protein you can use without digestive symptoms, use a dairy-free protein powder instead. Egg, soy, pea, or beef protein supplements are all effective and lactose-friendly.

Are Casein and Whey Protein Powders Vegan-Friendly?

No, casein and whey protein powders are not vegan-friendly. Both casein and whey are dairy-based proteins, which means they are animal products.

If you’re looking for a plant-based protein powder, try soy or pea protein for an excellent alternative proven effective for building muscle mass.

What Happens If You Consume Too Much Casein or Whey Protein?

Nothing bad!

Your body uses the protein to build other tissues in your body. For example, you also need protein to build and repair cells in your skin, gut, and organs like the liver. That’s where it goes if you eat more protein than your body can use to build muscle.

There is no practical limit to how much protein your body can use to build new tissue from a meal; it just won’t all be muscle.19 You don’t pee the protein out if you consume above-average amounts of protein in one sitting.

Likewise, high-protein diets overall are not harmful. No Tolerable Upper Intake Level for protein consumption has been established, and no adverse consequences (including cancer, kidney disease, kidney stones, and osteoporosis) of high protein intakes have been identified.20

If you consume more protein than your body can use for building and repairing tissue, it might be a waste of money, but you’re not harming your body. It simply uses it for energy instead.

Casein vs. Whey: Which Protein Powder Should You Choose?

Whether you’re looking to build muscle, lose weight, or improve your overall health, both casein and whey can be helpful as an addition to your daily protein intake.

Casein vs. Whey for Building Muscle

Protein supplements, be they casein, whey, soy, or pea protein, primarily impact your ability to build muscle by adding to your daily protein intake.

Research shows that consuming 1.6–2.2 grams of protein per kilogram (0.7–1 grams per pound) of body weight per day gives your muscles all the protein they need to grow.21

Read more:

>> How Much Protein Do You Need per Day to Gain Muscle?

If your regular diet does not provide enough protein, adding a protein supplement will likely help you build more muscle. Casein and whey are both excellent options in this scenario. 

If you already get sufficient amounts of protein from whole foods, adding even more from casein or whey protein powders will do nothing but increase your food budget and caloric intake.

Whey protein appears to be superior to others when ingested as the sole food source. However, that’s not typical of a real-life scenario. Both casein and whey protein are beneficial for building muscle when consumed as part of a balanced diet and strength training routine. 

The best option is likely the one you prefer.

  • Do you enjoy a smooth and tasty, easy-to-drink protein shake? Pick whey. 
  • Do you prefer creamy puddings and similar high-protein meals and recipes? Then casein might be the best option for you.

You can also get both and mix and match as you see fit. Some protein powders even contain a mix of both from the get-go.

Regardless, the most important thing when it comes to building muscle is overall protein intake. Ensuring you consume enough protein to support your muscle-building goals is key. Both casein and whey can help you do so.

I’ll pick whey protein if I have to recommend one or the other as a go-to protein supplement that ticks the most boxes. Whey is always a good choice regardless of the situation; it’s proven effective for muscle gain and relatively inexpensive, and most people find it the better-tasting option.

Casein vs. Whey for Reducing Muscle Breakdown

You might have seen claims that casein is ideal for reducing muscle tissue breakdown.

That is a misconception.

Contrary to popular belief, protein does not reduce muscle breakdown. Not directly.22 Insulin does.23

Your pancreas releases insulin whenever you eat or drink protein, reducing muscle protein breakdown. But it’s the insulin that’s responsible, not the protein itself.

In addition, it only takes a moderate increase in your insulin levels. Twenty to 25 grams of protein, either whey or casein, reduces muscle breakdown maximally. Increasing your insulin levels even more by consuming additional protein or adding carbs does not decrease muscle breakdown further.

In other words, insulin, not protein, halts muscle breakdown, and both casein and whey do the trick.

Casein vs. Whey for Fat Loss

Whey and casein protein can be part of a healthy weight and fat-loss diet. However, neither of the two will directly make you lose fat.

Protein increases the number of calories you burn more than fat and carbs and keeps you feeling full for longer. Therefore, a high proportion of calories from protein can help increase weight loss and prevent weight (re)gain.

Neither casein nor whey has a clear advantage when it comes to losing fat.24 25

You can choose the protein powder you like best as long as you maintain a high-protein diet and a calorie deficit. Going by taste and price is a good idea.

Casein vs. Whey: Conclusion

Casein vs. whey: let’s summarize!

  • Casein and whey are both milk proteins. You can get them from dairy products in your regular diet and protein powders derived from milk.
  • Both are complete, high-quality proteins that provide all the amino acids your body and muscles need.
  • The main difference between casein and whey protein is the digestion rate: whey protein is quickly absorbed by the body. In contrast, casein protein is digested more slowly and provides a sustained release of amino acids.
  • Whey protein is ideal for boosting muscle protein synthesis and is often used for post-workout recovery.
  • Casein protein does not spike muscle protein synthesis like whey protein; instead, it moderately elevates it for a long time, like during an overnight fast.
  • A particular type of protein powder will not necessarily improve your gains, but both casein and whey protein are great for increasing your daily total protein intake, and that can help you get the best results from your efforts in the gym.

Ultimately, both whey and casein protein can be part of a healthy diet for building muscle and losing fat.

Whey protein likely comes out on top if you can only pick one winner in the casein vs. whey battle.

Whey is the most versatile option, as you can not get isolated whey protein from your diet, while dairy foods like cheese and cottage cheese provide almost pure casein. In addition, whey protein is less expensive, blends more efficiently, and most people find it more palatable.

Overall, that gives whey a slight edge as a jack-of-all-trades option among protein powders. But regardless of which you prefer, casein or whey, you’re giving your muscles what they need to thrive.


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Andreas Abelsson

Andreas is a certified nutrition coach with over three decades of training experience. He has followed and reported on the research fields of exercise, nutrition, and health for almost as long and is a specialist in metabolic health and nutrition coaching for athletes. Read more about Andreas and StrengthLog by clicking here.