Written by Garett Reid | NSCA, CSCS, CISSN, M.S.E.S.S
Fact checked by Andrew Lenau, ISSA CPT & Sports Nutritionist
FACT CHECKED
Wait a minute, there’s another protein other than whey protein? If you’re one of those, who ask yourself that, you’re definitely going to want to read about the “other” protein called casein. If you have heard of casein but are still unsure what the deal is, you will want to read further about casein vs whey. Casein and whey are like peanut butter and jelly...no, like peanut butter and almond butter. They’re both excellent, and both have purposes. However, like almond butter, people don’t know enough about casein. In this article, we’ll fix that.
Here's what you'll learn:
- What is whey protein? What is casein protein?
- Similarities and differences between whey and casein protein supplements
- Unique benefits of casein protein powder
- Who should use whey?
- Who should use casein?
What Is Whey And Casein Protein?
If we’re going to talk about “what casein is” or “what whey is,” we might as well talk about both of them at the same time. That’s because whey and casein actually come from the exact same source and are much more “related” than most people think. Whey and casein are both milk-based proteins meaning that they come from mammals’ milk.
Now notice we said, “mammal” and not just “cows,” as many just assume. That’s because whey and casein protein are found in the milk of basically all mammals, including human breast milk. Yep, you drank casein protein as a little baby and didn’t even know it.
Actually, while everyone is talking about whey and cows, studies show the milk from a human breast has a significantly higher whey to casein ratio at 70% whey and 30% casein (actually 50/50 by the time milk is lactated but still)1! Speaking of, we have a protein powder idea we’re producing now called “Mama’s milk protein!” Would you buy it?
Anyways, enough about breasts. Let’s talk about udders because that’s where the vast majority of people are going to get their milk. As hinted above, most other mammals have a much lower whey to casein ratio. For example, cows are at about 20% whey to 80% casein! This means that even though whey is talked about much more frequently, cows produce 4X more casein.
So when milk is produced by cows and collected in tin buckets (because we think that’s how they still milk cows), the casein and whey proteins are all mixed up with all of the other compounds found in milk. In case you were wondering, 1 cup of raw milk has the approximate macronutrient breakdown:
- Calories - 160
- Protein - 9g
- Carbohydrates - 12g
- Fat - 9g
This means the cow’s milk is around 22-23% protein. As mentioned, out of these 9 grams of protein, casein makes up 80%, while whey makes up the last 20%. Anyways, the milk we drink (assuming the milk you drink comes from cows) is then sent off to pasteurization which degrades the nutritional quality slightly but generally leaves the same composition of 20% whey to 80% casein.
In order to make whey protein powder, it must be separated from the casein and other compounds. Whey will actually come from the milk shipped to cheese producers rather than milk distributors. Once the cheese producers receive the milk, they will first pasteurize it.
After, they will then introduce an enzyme complex called rennet. This enzyme will cause the milk to curdle, which means the casein protein will form into little solid balls. If you have ever had milk go bad and seen the solid chunks that form, that’s actually the casein.
After this process, what’s left is the curdled chunks of casein and a watery substance with the leftover whey proteins, fats, and carbohydrates (lactose). This watery substance is then shipped off to be further filtered and dried, and viola’! You have your whey powder.
A little bit more involved than that but that’s basically where we get whey and casein.
Similarities & Differences Between Casein and Whey Protein
So above, we basically talked about where casein and whey come from. Now we want to compare them and look at both similarities and differences.
1) Whey Has More Leucine Than Casein:
While whey and casein in powder form both have an excellent amino acid profile, whey comes out on top. This is for having an essential amino acids profile that’s more suitable for muscle protein synthesis (MPS) due to its higher branched chain amino acids (BCAA) content, especially leucine. Compared to casein at 8%, the leucine content of whey sits around 11% making it one of the richest leucine foods there is.
This is vital for muscle growth as leucine is the most essential amino acid for MPS; in fact, leucine is what triggers the entire process making it the most important amino acid for weight training. And in fact, that’s precisely what studies show. When comparing whey to casein, whey protein produces a higher spike in protein synthesis both at rest and after resistance training2. This is key for muscle growth.
However, there’s another quality of whey that could cause this higher spike in muscle protein synthesis.
2) Whey Protein Is A Fast-Acting Protein, Casein Slow Acting:
You’ve probably heard that whey protein is a “fast-acting” protein before. What this means is that whey is easier to break down and digest into amino acids. Once the amino acids have reached “free form,” they can enter the bloodstream to be used for muscle recovery.
Not only does your body break down whey protein faster, but doing so gives it a “bigger hit” of amino acids resulting in a larger spike. This is perfect for right after your workout as your muscles are craving amino acids for repair.
On the other hand, your body has difficulty breaking down casein due to its makeup. Remember how they are produced; whey stays a liquid while casein solidifies. Anyways, because it takes longer to break down, a smaller stream of amino acids is released into your bloodstream, resulting in a smaller peak.
However, because casein breaks down slower, the smaller peak will remain for a more extended period of time. In fact, some studies have reported the difference in duration has been 90 minutes for whey and 4-5 hours for casein3. This is probably the biggest difference between casein and whey, and what affects purchase decisions.
3) Casein Tends To Be More Satiating:
To begin with, of all macronutrients, protein is the most satiating. This means that if you were to eat 200 calories of carbs, 200 calories of fat, and 200 calories of protein, the protein is going to keep you feeling fuller much longer.
One of the reasons for this is that protein is hard to break down. If you were to think about food sources, what do you think is more difficult to digest; chicken breast (protein), banana (carb), or oil (fat).
However, above, we just talked about how whey is a fast-acting protein, which is digested easier than casein. This means that casein sits in your digestive tract for a longer time, which can keep you feeling fuller.
In fact, when you mix a whey protein shake and a casein protein shake, the casein is significantly thicker. It’s common for people to report that a casein shake with the same caloric value as whey is considerably more fulfilling. This can make casein a great option for fat loss.
4) Casein Is Usually More Expensive:
While this doesn’t seem to be as drastic anymore, casein seems to be a little more expensive than whey. For example, we can compare the prices of a whey protein from Dymatize and a casein from Dymatize
- Dymatize Elite 100% Whey: 67 servings/25g protein: $59.79
- Dymatize Elite Casein: 50 servings/25g protein: $62.33
**Just a heads up, there are affiliate links in this post where we will receive a small commission if you purchase at no cost to you. We only recommend products we think our audience will find valuable.**
So while casein is a few dollars more, you get 17 fewer servings. Still, when compared to a whole food, whey and casein are both cheap protein sources.
Caseins’ Unique Advantage
Casein does hold one unique advantage over whey that can’t be duplicated by whey. That is, casein works excellent as a pre-sleep protein.
To be clear, this doesn’t mean nighttime protein; this means you purposefully drink a casein protein shake 30 minutes before you go to sleep. Due to it being a slow-digesting protein, it can maintain elevated levels through the majority of your sleep!
This massive chunk of time was greatly ignored until recently; sports researchers started to think if we’re just wasting this period of time for recovery. Turns out we are. Concerning drinking casein before sleep, a meta-analysis concluded:
“The consumption of 20–40 g of casein approximately 30 min before sleep stimulates whole-body protein synthesis rates over a subsequent overnight period in young and elderly men…In addition, pre-sleep protein consumption can augment the muscle adaptive response (muscle fiber cross-sectional area, strength and muscle mass) during 10–12 weeks of resistance exercise in young (men).4"
Again, this benefit is unique to casein due to the fact it is slow digesting. We should also mention that studies show that casein decreased protein degradation best when using relatively large doses, with 30-40g being the most beneficial.
Who Should Use Whey?
Whey protein has been around forever and is the go-to protein source for the majority of athletes. However, when comparing whey with casein, it really only has one major benefit, albeit a big benefit. That protein is a fast-acting protein with a high leucine content, making it perfect for a post-work shake. Being that this is the primary reason people take protein shakes, it’s a pretty significant benefit.
Therefore, any athlete or weight lifter can benefit from whey protein as a post workout protein source.
100% WHEY PROTEIN ISOLATE - a high-quality protein source providing 25g per serving to support muscle building and recovery...
Who Should Use Casein?
Even though casein is lesser-known than whey protein, it’s actually a much more versatile protein source. In fact, with more research being done on casein, it’s becoming the go-to protein source for general use.
Most people just assume that because whey protein is fast-acting and causes a higher spike, it’s the better protein source. While this might be true for post-workout, there’s no research to suggest that this higher spike in amino acids has any other benefit. For example, if you are at work and have a protein shake for a snack, there’s no reason you need a fast-acting protein.
However, because it is a slow-digesting protein, that spike remains for a longer period of time. Therefore, unless you have a shake post-workout, a casein shake might actually be the more suitable choice. For example, if you like to make a protein shake in the morning, using casein will leave you with elevated levels well into lunchtime.
At the same time, casein could also play a bigger role in weight loss. As mentioned, protein, in general, is extremely beneficial in contributing to fat loss, and high protein diets are highly effective in weight loss. However, due to caseins consistency, it could help keep you feeling sustained for longer and curb cravings.
Finally, we can’t forget about casein’s benefit as a pre-sleep protein. That can basically help everyone. If you want to see what your options are, check out a full breakdown of the best casein powders on the market right now.
Recover while you sleep: help prevent muscle loss overnight with this slow-digesting protein...
Whey vs Casein Protein Powders: Final Verdict
They’re both fantastic! The only negative thing we would say about either is that too many people have acted as if whey is the only protein source for too long. To be clear, whey is incredible and likely the best choice for a post-workout protein choice.
However, there are other proteins out there that are better for different circumstances. In fact, whey itself has different variations such as hydrolyzed whey. Regardless, casein is another protein source and is much more versatile while bringing some unique benefits.
At the end of the day, here is how we would suggest using whey and casein protein powders:
- Use whey protein supplementation for your post-workout protein source.
- Use casein as a general-purpose protein supplement.
- Use casein for a meal replacement for weight loss.
- Use casein as a pre-sleep protein.
If you want to further your understanding of whey protein powder, we also did a write-up on the differences between whey protein concentrate and whey isolate: Whey Concentrate vs Whey Isolate.
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References:
- Martin C, Ling PR, Blackburn G. Review of Infant Feeding: Key Features of Breast Milk and Infant Formula. Nutrients. 2016;8(5):279. doi:10.3390/nu8050279
- Tang JE, Moore DR, Kujbida GW, Tarnopolsky MA, Phillips SM. Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. Journal of Applied Physiology. 2009;107(3):987-992. doi:10.1152/japplphysiol.00076.2009
- Dangin M, Boirie Y, Guillet C, BeaufrèreB. Influence of the Protein Digestion Rate on Protein Turnover in Young and Elderly Subjects. The Journal of Nutrition. 2002;132(10):3228S3233S. doi:10.1093/jn/131.10.3228s
- Reis CEG, Loureiro LMR, Roschel H, da Costa THM. Effects of pre-sleep protein consumption on muscle-related outcomes — A systematic review. Journal of Science and Medicine in Sport. Published online August 2020. doi:10.1016/j.jsams.2020.07.016
Garett Reid
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