If you're trying to build muscle or lose body fat, getting enough protein is crucial. It helps with building and maintaining muscle, no matter what the goal is.
Ideally, you'll get most of your protein from food. However, that's not realistic for everyone living a busy lifestyle. Many people have turned to protein powders to help them get more of it every day.
But with all the types of protein powders out there, it can get confusing. One of the biggest questions people ask is: "What's the difference between whey vs casein protein?"
It's a great question, and understanding the answer can help you make smarter choices for your goals!
I'll break down whey vs casein so it's easy to understand, and even easier to put into action.
In This Article:
• What Are Whey and Casein Proteins?
• The Main Differences Between Whey vs Casein Protein
• Which One Is Better: Whey or Casein?
• What Is a Rapid Assimilation Protein
• What Is a Sustained Assimilation Protein?
• Don’t Forget Your Total Daily Protein Intake
• Frequently Asked Questions About Whey vs Casein
• Final Thoughts: Use the Right Protein at the Right Time
What Are Whey and Casein Proteins?
Whey and casein are both proteins that come from milk. They're both high-quality proteins, too!
When it comes to the protein in milk, about 20% is whey, and the other 80% is casein. That means every time you drink a glass of milk, you're getting a mix of both.
These proteins can be separated, concentrated, and turned into powders that we use for supplements. But even though they come from the same place, whey and casein act very differently once they're in your body.
The Main Differences Between Whey vs Casein Protein
1. Digestion Speed
Whey protein digests quickly. Casein digests slowly.
A whey protein shake can be digested in as little as 2 hours (1). This, of course, depends on what type of whey protein is used. There are 2 main types of whey protein out there, but I'll get to that in a bit.
That's why whey protein is perfect to use right after your workout, though. Your muscles get the amino acids they need faster than most whole foods can provide!
Casein, on the other hand, digests slowly. It may take up to 4 to 6 hours or even more (2). That makes it a better option when you know you won't eat for a while, like before bed.
2. Amino Acid Content
All protein is made of amino acids, but some are more important than others.
Both are packed with Essential Amino Acids (EAAs), but whey is especially high in leucine. Leucine is the amino acid most responsible for stimulating muscle protein synthesis (MPS). Think of this as the body's state of repairing and building muscle tissue.
Casein still has a good amount of leucine, but not as much as whey. Both also have plenty of glutamine, which is the most abundant amino acid in muscle tissue.
Casein has more glutamine than whey does, though. With all of that being said, both proteins are beneficial for muscle growth and fat loss (3).
They're just better used in different situations. I'll cover that in the next section!
Complete Whey vs Casein Protein Comparison
Here's everything you need to know about whey vs casein protein in one comprehensive table:
| Feature | Whey Protein Isolate | Whey Protein Concentrate | Casein Protein |
|---|---|---|---|
| Digestion Speed | Fast (1–2 hrs) | Medium (2–3 hrs) | Slow (4–6 hrs) |
| Best Time to Use | Post-workout | Between meals | Before bed |
| Leucine Content | Highest | Higher | Good |
| Glutamine Content | Good | Good | Highest |
| Mixability | Excellent | Very Good | Good (can be thick) |
| Taste Profile | Clean, light | Creamy, rich | Thick, creamy |
| Lactose Content | Very Low (<1%) | Low (2–8%) | Low (2–5%) |
| Primary Benefits | Recovery, muscle growth | Slow-digesting for meals and snacks, muscle growth & repair | Muscle preservation |
| Best For | Athletes, post-workout | General fitness, snacks | Nighttime support |
So Which One Is Better: Whey or Casein?
It depends on when you're using it.
If you just finished a workout and want to kick-start recovery, whey protein is the better choice. It digests fast, delivers more leucine, and supports quicker muscle repair.
If you're heading to bed or know you won't eat for a while, casein protein is a great tool. Its slow digestion helps feed your muscles over time and prevents muscle breakdown.
But what if you want the best of both worlds? Well, no one said you can only use one type of protein supplement!
There are different protein supplements designed for different purposes. You can choose whichever one you need, depending on when you need to use one.
So to answer this question about whey vs casein, neither is better. They both have their place and can play different roles in your diet.
What is a Rapid Assimilation Protein?
A rapid assimilation protein is a type of fast-digesting protein powder. These are best used right before or after a workout because of how quickly they're absorbed.
When you finish training, you've just broken down your muscle tissue. Your body is then primed and ready to start rebuilding!
With a rapid assimilation protein shake, you can kick-start the recovery process. A slower-digesting protein source will take longer to do the same thing.
The best type of protein for rapid assimilation is whey protein isolate. This is different from other types of whey, like whey protein concentrate. Let me break this down really quickly.
When whey protein is first made, it still contains lactose and fats. Most of the lactose and fats get filtered out to make different concentrations of protein.
Whey protein isolate contains 10% or less lactose and fats. This allows it to break down and digest faster, being more of a pure protein source.
Whey protein concentrate contains 10-20% lactose and fats. The extra lactose and fats allow for a slower breakdown. This makes it more of a sustained assimilation protein, and I'll cover more on that in the next section.
What Is a Sustained Assimilation Protein?
A sustained assimilation protein is a type of slower-digesting protein powder. It's designed to mimic the digestion of a whole food protein source!
This gives your body a steady stream of amino acids to absorb for hours. This makes it a perfect meal replacement or snack, especially when you can't get real food in.
This could be done with casein, but it could also come from whey protein concentrate. It could also be a blend of them.
Casein digests much more slowly than whey concentrate, but may not stimulate muscle protein synthesis quite as much. In my opinion, casein is best used before bed to feed your muscles while you sleep.
I like whey protein concentrate for a protein replacement throughout the day. It digests more slowly than whey isolate, and still spikes muscle protein synthesis well!
Don't Forget Your Total Daily Protein Intake
It's not just about what type of protein you get in the whey vs casein debate. It's also about how much protein you eat every day!
Your body needs protein to:
• Rebuild muscle
• Support your immune system
• Grow healthy hair, skin, and nails
• Produce hormones and enzymes
...and if you're trying to lose body fat, hitting your protein goal helps you hold onto lean muscle. The more lean muscle you have, the more calories you can burn at rest. Not only that, but it helps to keep you full. That can help you better stay within your calorie range needed to lose body fat!
So, how much protein do you need? I always recommend staying between 1 gram of protein per pound of your goal weight and your current body weight.
That is sufficient for any goal you have for muscle growth and fat loss.
Frequently Asked Questions About Whey vs Casein
Q: Is Whey or Casein Better for Building Muscle?
A: Both can be great tools used for building muscle in the whey vs casein comparison. They are just best used at different times for different purposes!
Q: Can I Take Both Whey and Casein?
A: Yes! Many people use whey isolate after workouts and whey concentrate for meals and snacks. Casein is most often used as a pre-bedtime protein.
Q: What Is Sustained Assimilation Protein?
A: Sustained assimilation proteins are slower-digesting protein shakes. These are most often whey protein concentrate, casein, or a blend of different proteins.
Q: Is Casein Protein Better at Night?
A: Yes. Because casein digests slowly, it can help prevent muscle breakdown while you sleep.
Q: Which Is More Expensive: Whey or Casein Protein?
A: In the whey vs casein price comparison, they're typically similar. Whey isolate tends to be the most expensive, followed by casein, then whey concentrate, as the most affordable option.
Q: Does Whey or Casein Taste Better?
A: This is subjective, but whey proteins generally mix smoother and have cleaner flavors. Casein can be thicker and more pudding-like, which some people love for dessert-style shakes.
Final Thoughts: Use the Right Protein at the Right Time
Both whey and casein have their benefits, and both can play a role in helping you hit your fitness goals. I've used them both over the years, and they can help you see pretty awesome results!
Over my years of training clients, I've helped thousands of people with their diet. Based on the results I've seen, I've always been a bigger fan of whey protein than casein.
That's not to say that casein isn't beneficial. It's just a tool that I find is less versatile than whey protein tends to be.
Whey protein isolate is such a dynamic tool to help people recover quickly after workouts. This kickstarts the muscle-building process faster than anything else I've ever seen!
Whey protein concentrate is versatile in that it digests at a moderate pace over a few hours. It's a high-quality protein that can bridge the gap between meals perfectly. If you use it wisely, you could keep yourself in a state of muscle protein synthesis most of the day.
Casein is the slowest digesting protein powder I'm aware of. It has a strong anti-catabolic effect, which counteracts muscle protein breakdown well. That's why it works so well as a pre-bedtime protein.
It can feed your muscles for a long time while you sleep. That's when I've found it to be best utilized.
If you're looking for the most optimal post-workout protein shake, check out our Post Workout Stack at 1st Phorm. It contains 2 products:
Phormula-1 - a high-quality whey protein isolate. It's designed to kickstart recovery after exercise as fast as possible.
Ignition - a high glycemic carbohydrate powder. It's designed to help support energy replenishment, decreased muscle soreness, and improved overall recovery.
I've been using it for 13 years now, and it's by far the best recovery stack I've ever found! If you have issues with lactose, check out Phormula-1 Clear. It's a clear whey protein with zero lactose, lower calories, and all the same benefits of whey protein isolate. It is also available in the Clear Post Workout Stack.
When it comes to meals and snacks, Level-1 has been my go-to. It's a high-quality whey protein concentrate that can keep you full between meals and help you see awesome results.
We also offer a 100% plant-based protein option called Vegan Power Pro. Vegan Power Pro is sourced from pea protein and rice protein for a well-rounded amino acid profile. You can use it for post-workout recovery as well as for getting more protein in throughout the day!
Regardless of what you choose to use in the whey vs casein decision, just make sure you're using your protein supplements at the right time. That way, you get the most out of them and their individual benefits!.
If you have any questions about whey vs casein protein in the meantime, don't hesitate to reach out. We have a full team of NASM Certified Personal Trainers and Nutrition Coaches right here in St. Louis, Missouri.
Just give us a call at 1-800-409-9732 or send us an email at CustomerService@1stPhorm.com any day from 6 AM to 10 PM Central. We'll be more than happy to help any way we can!
References:
(1) Schoenfeld BJ, Aragon AA. How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution. J Int Soc Sports Nutr. 2018;15:10.
(2) Gorissen SHM, et al. Protein Type, Protein Dose, and Age Modulate Dietary Protein Digestion and Phenylalanine Absorption Kinetics and Plasma Phenylalanine Availability in Humans. J Nutr. 2020;150(8):2041-2050.
(3) Wilborn CD, et al. The Effects of Pre- and Post-Exercise Whey vs. Casein Protein Consumption on Body Composition and Performance Measures in Collegiate Female Athletes. J Sports Sci Med. 2013;12(1):74-79.
