Whether you are a bodybuilder, CrossFitter, Strongman, powerlifter, or runner, a protein supplement will be a part of your fitness regimen.
More importantly, the reason we are taking a look into the whey vs. casein debate is that nothing can divide a room full of muscle-hungry bodybuilders like an argument about the best source of protein for recovery and muscle growth.
Ask your friendly-neighborhood gym bro how you can build muscle quickly, achieve a personal best on the bench press, or recover faster, and he’ll push a protein supplement down your throat. Although the gym bro might look like a tacky salesman, he’s right about the benefits of a protein supplement.
The sports supplement market is flooded with protein supplements. You can get yourself dairy-based (whey and casein), egg, beef, collagen, or even plant-based (pea, soy, hemp, or rice) protein supplements. Nonetheless, whey and casein are the most popular protein supplements.
In this article, we discuss the benefits, differences, macronutrient breakdown, and the best method of taking whey and casein supplements to make the most of them. We will also look at both with regard to their contribution towards recovery, growth, anti-catabolic properties, and health via immunity enhancement.
Whey and casein proteins come in different forms. However, we will stick to whey concentrate and micellar casein to keep the comparison fair and square. This will be the veritable battle to end all of the indecision.
Benefits of a High-Protein Diet
Cow’s milk contains whey and casein proteins. Whey protein makes up 80% of the milk protein, whereas casein takes care of the remaining 20%. Each whey and casein protein contains all nine essential amino acids (EAAs), making them a complete protein source. You must get the essential amino acids from your diet as your body cannot make them. 
Before we get into the nitty-gritty of the whey vs. casein debate, let’s touch upon the benefits of a high-protein diet and why you should bother with protein supplements in the first place. We’ll get to the specific benefits of whey and casein protein later in this article.
- Helps Build Strength and Muscle Mass: This is the main reason why strength sports athletes use protein supplements. Protein is the main building block of muscle, and eating adequate protein can help maintain and build muscle mass.
- Boosts Weight Loss: Protein keeps you full for longer, reducing your chances of binge eating junk food. It also reduces your appetite and hunger levels. Sticking to high-protein diet aid in keeping the lost weight off. 
- Improves Bone Health: Folks that eat a protein-rich diet maintain their muscle mass with age. They also have a lower risk of developing osteoporosis and fractures.
- Lower Blood Pressure: Higher protein intake has been shown to lower blood pressure. 
- Helps With Recovery After Injury: Besides helping with muscle recovery after a workout, a high-protein diet also improves recovery after an injury.
How are Whey and Casein Made?
Although both are by-products of cheese production, whey is the more common of the two protein sources. Until whey and casein were discovered to have a value, they were just discarded.
During the cheesemaking process, the addition of special enzymes to heated milk results in the coagulation of casein in the milk. The liquid left behind is whey protein. This liquid leftover is then washed and dried into a powder form to use in food products or to be sold as a dietary supplement.
The remaining casein protein is washed and dried to be sold as a dietary supplement. Alternatively, you can add it to dairy products like cottage cheese and Greek yogurt.
What is Whey Protein?
Whey protein is the most popular protein supplement. It is the supplement you see your favorite bodybuilder gulp right after a workout, first thing after waking up, or a couple of hours before they hit the gym. We know what you are thinking. And yes, you got it right. Elite bodybuilders use a lot of whey protein powder.
This is the protein every supplement company will have you believe adds muscle to your frame as quickly as you can drink it. Walk into any sports nutrition store, and you risk being crushed by the mountainous piles of whey powders.
The reason for the outrageous claims of massive muscle growth is that whey is a relatively fast-digesting protein that delivers amino acids to the bloodstream within an hour.
Whey protein concentrate has also been proven to increase protein synthesis, a major muscle recovery and growth component. These two facts are the basis for most marketing campaigns for whey supplement-producing companies.
Whey is rich in branched-chain amino acids (BCAAs), which is why it increases protein synthesis. It also contains lactose, but not as much as casein, as well as some vitamins and minerals.
A unique portion of whey’s content is lactalbumin. Lactalbumin is found in the milk produced by many mammals and is very similar to breast milk in many respects.
Furthermore, whey has an antioxidant effect because it enhances glutathione levels. Glutathione is a tri-peptide that contains one amino residue from the amino acids glutamic acid, cysteine, and glycine. Glutathione plays a major role in protecting skeletal muscle and other bodily tissue from oxidative damage. This is important, considering all forms of training will result in some degree of oxidative stress. Glutathione also helps maintain iron in its proper oxidation state in hemoglobin, another valuable contribution of whey protein powder.
Whey Protein Isolate and Hydrolysate
Almost everything except the protein is stripped away when making whey protein isolate or hydrolysate. Whey protein isolates and hydrolysates undergo subsequent filtration processes to yield a higher protein concentration with minimal lactose and fat content.
Whey isolates and hydrolysates are still excellent sources of the amino acid cysteine, and high cysteine levels are considered effective at replenishing whole blood glutathione. Maybe not as effective as a concentrate, but there may still be an immunity-boosting property to the more refined forms of whey protein powders.
What is Casein Protein?
Casein protein is extremely slow-digesting when compared to whey protein. Like whey protein, it also offers a complete amino acid profile, meaning it contains all nine EAAs, but has a lower leucine content.
Due to its long digestion time, it retains nitrogen very well, and a positive nitrogen balance is required for an anabolic response to occur. That’s one huge plus for casein and something that whey protein lacks.
Due to its slow-digesting property, fitness enthusiasts take a casein supplement before going to bed. Most lifters sleep for seven to eight hours each night and eat something 1-2 hours after waking up. This 9-10 hour fasting period can lead to muscle loss. Taking a casein supplement before bedtime ensures a constant supply of protein to your muscles, which not only prevents entering a catabolic state but also helps build and maintain muscle mass.
Casein is, not surprisingly, a great source of calcium. Calcium has a few different things going for it for fitness enthusiasts. From any kind of training, from high-impact sprint drills to heavy-weight training, your bones will be put under stress. Calcium is famous for its bone health benefits.
Calcium also performs a couple of pretty awesome functions when it comes to body composition. First, for whatever reason, it is extremely thermogenic, which is a major boon, especially considering casein’s slow-digesting properties. Thermogenesis is the process of heat production in humans. This means that if you are creating heat because of the calcium in casein, then you are using more energy during its digestion than you would with whey. Calcium also inhibits fat absorption, yet another positive for casein as a protein for fat loss.
Micellar Casein and Casein Hydrolysate
Micellar casein and casein hydrolysate are the two main types of casein. The former undergoes minimal processing, retaining its natural structure and slow-digesting properties. However, the latter is pre-digested, resulting in faster absorption rates than micellar casein.
You must choose between the two based on your goals. Folks that take the casein protein close to hitting the sack should prefer the micellar protein because of its slow-digesting properties. Lifters who take casein after their workouts can opt for the hydrolysate variation.
Main Differences — Whey vs. Casein
The absorption rates are the biggest difference between whey and casein proteins.
Whey is a Fast-Acting Protein Best For Taking After a Workout
Due to its quick-absorbing property, whey protein is the go-to supplement for lifters to consume right after their workout. It leads to a quick release of amino acids into the bloodstream, which kickstarts the recovery and muscle-building process.
Whey protein contains more branched-chain amino acids (BCAAs) — leucine, isoleucine, and valine than casein. Although all amino acids are required for building muscle, leucine helps kickstart the process.
Many lifters consume their protein shake within the 30-minute ‘anabolic window’ after a workout for better muscle gains. However, recent research has shown that your daily protein intake is a better predictor of muscle size and strength growth than when you consume your post-workout shake. 
Casein is a Slow-Digesting Protein
Casein protein’s slow-digesting property makes it a poor candidate for pre-training nutrition. It forms a gel-like substance in the stomach, resulting in slower digestion and a gradual amino acid release over four to five hours. Comparatively, amino acid levels in your body remain elevated for up to 90 minutes after consuming a whey protein shake.
Furthermore, casein has a high-lactose content. Lactose-intolerant people will not be able to consume casein. Also, the high sodium content of casein concentrate is not ideal for a competitive bodybuilder or an athlete such as a wrestler trying to make weight. Notably, sodium content is not an issue with some casein hydrolysate products.
In one study where the amino acid leucine was used as a marker to measure amino acid levels in the blood, whey concentrate peaked after one hour of consumption and returned to baseline levels after four hours. Casein has a much lower leucine content and peaks later but didn’t return to baseline levels for seven hours.
Whey showed a postprandial protein synthesis stimulation increase of 68 percent but showed nothing relating to protein degradation inhibition. Casein, on the other hand, decreased protein degradation by 34 percent. Postprandial whole-body leucine oxidation was lower with casein than with whey, but because it was measured to be in the bloodstream for seven hours, the net amount was greater than with whey. So whey is faster, but casein’s slow and steady approach wins in terms of volume.
Macronutrient Breakdown of Whey and Casein Protein
Although whey and casein protein supplements have different properties — one absorbs within 90 minutes while the other takes up to five hours, their macronutrient content is similar.
For the scope of this article, we will share the macronutrient content of Optimum Nutrition Gold Standard Whey and Casein protein:
Optimum Nutrition Gold Standard 100% Whey Protein Powder
A 32g scoop of ON 100% whey protein supp contains:
- Calories: 120
- Fat: 2g
- Carbohydrates: 3g
- Protein: 24g
- Iron: 6% of the RDI
- Calcium: 10% of the RDI
Optimum Nutrition Gold Standard 100% Micellar Casein Protein Powder
A 34g scoop of ON 100% casein protein supp contains:
- Calories: 120
- Fat: 1g
- Carbohydrates: 4g
- Protein: 24g
- Iron: 8% of the RDI
- Calcium: 40% of the RDI
How To Use: Whey vs. Casein
How you use whey and casein supplements can depend on your preferences.
You could consume a whey protein shake after a workout for faster recovery, as your body requires immediate amino acid delivery. Protein supplements come in different flavors, which makes them great to mix with water, milk, or a beverage of your choice. You could also combine the whey protein powder in a recipe to spike your daily protein intake.
The slower digestion and sustained amino acid release offered by casein protein make it an ideal nighttime protein supplement. Consuming a casein protein shake during the day can make you feel fuller for longer than whey protein. You could switch to a casein hydrolysate if the micellar version feels too heavy on your stomach.
We recommend sticking to the recommended dosage mentioned on the container of your whey or casein supplement.
Which One Is Best For You?
Contrary to what most people think, you don’t have to use an either-or approach with whey and casein protein. Each protein has its unique benefits and can fit into most fitness enthusiasts’ lifestyles.
A lifter could drink a whey protein shake 2-4 hours before a workout or within two hours of finishing a training session to kickstart his recovery. Whey protein powders are incredibly versatile and can be included in several dishes and recipes.
On the other hand, the casein protein is best taken before hitting the sack, as it ensures that your muscles get a constant supply of protein throughout the night. The slow-digesting property of casein prevents your body from entering a catabolic state, where it breaks down muscle tissue to use as an energy source.
Can taking whey and casein protein supplements harm kidneys?
According to the undying myth, consuming a high-protein diet can damage the kidneys and liver. However, several studies have concluded that high-protein diets have no harmful effects on people without kidney disease. Nonetheless, people with kidney issues should limit their protein intake to avoid further kidney condition deterioration. 
Is there a difference between the taste of whey and casein protein?
Yes. Although both types of proteins come in several flavors, whey is popular for its amazing taste. On the other hand, casein protein has a much thicker texture than whey and can taste like a thick smoothie, even when mixed in water. The taste of casein protein is a hit or miss for most people.
Can lactose-intolerant people consume protein supplements?
Casein protein contains lactose. Lactose-intolerant people should opt for whey protein as lactose is removed during the refining process. Whey protein isolate and hydrolysate are best for lactose-intolerant people.
Whey protein is a faster-digesting protein that is great to consume after a training session. On the other hand, the slow-digesting property of casein makes it a perfect bedtime protein supplement.
Although people always want a decisive answer in every situation, sometimes there is no clear-cut winner; the whey vs. casein debate is an example of one of those times. You must assess your needs, preferences, and fitness goals while choosing between casein and whey protein. Both whey and casein have positives, and you can get desired muscle-building results by combining the two supplements. So feel free to take a scoop of each to recover faster and prevent catabolism.
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