Out of all the supplements out there, protein powder is the closest supplement to being “required” in lifting. Along with muscle gain and weight loss, whey protein has even been shown to lower cholesterol, help keep blood pressure in check, and reduce the risk of developing cardiovascular diseases.
Protein powders that are animal-based, such as whey and casein, provide a complete protein that’s guaranteed to boost your strength development and muscle building.
There’s a reason that protein powder (and specifically whey protein powder) is so ubiquitous in lifting circles. It hits your muscles fast and hard and leaves you with more energy to finish your workouts and an easier recovery.
The less popular cousin of whey is casein protein powder.
Usually relegated to more advanced lifters, this supplement has its own unique benefits that elevate it above whey in many ways.
However, due to their similarities, it’s often difficult to decide which one’s right for you.
Both whey and casein are milk protein that comes from cow’s milk, and they both offer a complete, high-quality protein.
They’re some of the most popular dietary supplements that ensure a consistent protein intake. They work amazingly well alongside resistance training to elicit muscle growth and strength gains.
So, what’s the difference? The big difference is that whey has a higher absorption rate, while casein is essentially the slow-release version.
Although this sounds like a simple difference upfront, it does have interesting ramifications when it comes to the question of building muscle mass.
While whey offers a quick and clean dose of protein (and the important amino acids), casein takes longer to digest and be absorbed in your body.
This means that it can prevent protein breakdown over longer periods of time. We’ll explore what this means further down below. And while casein and whey come from the same source, they also have differences in the protein profile they provide.
But what does this actually mean?
There are thousands of different types of proteins in our bodies. These are all made from over 20 different amino acids. Arranging the amino acids in different ways will give you a different protein. While most of these can be produced by our bodies, nine of them cannot. These are known as the essential amino acids (EAAs) and they have to be consumed in sufficient quantities for optimal wellness.
They include:
Although both casein and whey are dairy products, they differ in their amino acid profile. For example, casein includes higher proportions of methionine, histidine, and phenylalanine.
On the other hand, whey includes higher proportions of leucine, isoleucine, and valine. But both proteins are still considered complete, in the sense that they offer all of the EAAs that our bodies need.
This is starkly different from plant-based protein powders, where only soy protein is considered complete. Certain amino acids are also considered branched-chain amino acids (BCAAs). Because they’re found often in muscle tissue, it’s believed that they have the greatest impact on muscle and strength gain.
Whey is a by-product of the cheese-making process—it’s the liquid part that remains after milk curdles. Up until relatively recently, it was thrown out by manufacturers until its benefits as a protein source were realized.
Whey goes through various stages of processing which refines the amount of protein relative to the carbs and fats.
It mixes well with water and milk, making it an accessible option for most people to include in their diets.
Whey protein powder is a relatively cheap and powerful source of extra protein that can supplement our diets.
Aside from the conventional benefits of a high protein diet, whey protein powder also has some of its own unique benefits:
Casein is the slow-digesting counterpart to whey.
It also makes up the majority of the protein found in milk, upwards of 80%. Since casein is processed differently (and is directly derived from milk rather than being a by-product), it’s going to break down much more slowly in your body.
This means that it’s going to keep you satiated for longer, which can be beneficial during fasts and before going to sleep.
This also means that your muscles will be getting a constant flow of amino acids to use, instead of breaking down.
Both casein and whey will lead to increased protein synthesis, however, whey leads to a fast spike of protein synthesis that doesn’t last too long.
Here are some of the benefits of casein:
Therefore, while whey protein is considered anabolic, casein is known as an anti-catabolic.
If you’re serious about bodybuilding or just looking your best in general, casein is an amazing supplement to add to your routine. Although it can’t achieve the same short-term benefits as whey protein, it’s still an integral part of building a jacked physique.
There are also other compounds within casein that separate it from whey.
Along with calcium, casein is a good source of different peptides.
These peptides benefit you in several different ways:
There are three different types of whey that differ based on how much it’s been processed.
Starting with the least processed is whey protein concentrate.
While it’s the most bioavailable of the whey proteins, it also contains a significant amount of carbs and fats when compared to the protein level. This makes it useful as a meal replacement, but not so useful when you’re trying to stay lean.
Whey protein isolate is the next most processed variety.
By putting it through further microfiltration processes, much of the carbs are filtered out of the whey, leaving more protein.
Lastly is whey hydrolysate (hydrolyzed whey). This form is essentially “pre-digested,” meaning that your body absorbs it extremely quickly. It also has the highest amount of protein per gram.
Just like whey, casein also comes in different levels of processing. However, this is less of a purification difference.
The first type is called micellar casein. A micelle is a structure that’s found in milk, and when all of its proteins are left intact, it’s very bioavailable. However, when some of the proteins aren’t there, the body has a more difficult time digesting them.
Micellar casein relies on a production method that keeps these structures intact, making the protein powder significantly more useful (and expensive).
There is also casein hydrolysate, which takes the processing much further. While micellar casein attempts to keep the micelle structures intact (which means processing has to be limited), casein hydrolysate goes the opposite direction when it comes to processing.
Just like whey hydrolysate, the casein version is essentially “pre-digested” for you, allowing very rapid absorption in your body. This happens to be one of the most expensive protein powders out there, but you do get a good dose of protein per gram of powder.
But you might be asking, what makes it different from whey hydrolysate? The answer is insulin.
The level of certain amino acids in casein allows for an increase in insulin levels—more than whey protein. And insulin is another anabolic hormone that not only raises muscle protein synthesis but also introduces carbohydrates into the muscles. These factors more casein hydrolysate the crème de la crème of protein powders.
So, now that we know what’s what, we can better answer the big question: is whey or casein better?
And as you can probably guess by now, the answer is a mix of the two.
Whey and casein both have their niche uses when it comes to protein supplementation. To optimize muscle growth and training, combining a fast-acting spike along with a slow-acting burn makes the most amount of sense.
The whey will power you through your workouts and give your muscles a spike of amino acids to work with while they’re being gassed out.
On the other hand, casein will slowly be absorbed into your body, giving your muscles the energy they need not break down their own protein.
However, most people won’t actually need both of these supplements to see results. Creating a set of achievable goals while also understanding your starting level is the first step in making wise supplement decisions.
This will allow you to optimize your routine and get the best bang from your buck out of the supplements you do choose to use.
When it comes to training consistently and maintaining your strength and muscle mass, a combination of whey and casein is going to be extremely useful.
This is going to be particularly important for bodybuilders who need to cultivate a ton of lean muscle mass. This means that their diet and routine have been dialed down to the most minuscule details. Introducing casein to go along with whey is pretty essential.
Supplementing with whey around workouts and supplementing with casein before bed is the way to go.
The whey will give you a boost to muscle protein synthesis while the casein will protect your gains from breaking down.
For beginners, there’s significantly more leeway. When you’re just starting out in lifting, your body goes through a process of recomposition. It’s much easier to gain muscle mass while shedding body fat at the same time. The amount of specialized training and dieting doesn’t have to be top tier to get results.
Beginners should focus on tuning in their diet throughout the day, instead of relying on supplements to maintain their muscle mass.
Chances are, at least in the beginning, that anything more than a whey supplement won’t be used to its fullest extent. And this is important, especially when considering the price.
There’s also the question of price. Whey is a leftover product from the cheese-making process. Next time you open a container of yogurt, notice the watery liquid sitting on top—that’s whey.
So, it’s not hard to imagine why whey is a relatively cheap and plentiful source of protein.
Manufacturers don’t have to really go out of their to produce it, since it’s a by-product of different manufacturing processes (that are also much popular).
Casein is different since it’s actually created directly from cow’s milk. This is obviously going to drive up the price, and whether it’s worth it depends on your goals and current fitness level.
The last difference between whey and casein is surface level, but it’s still important to consider the practicalities of implementing one or the other into your routine.
Part of whey protein’s popularity comes down to its accessibility.
Simply mixing it with some water or milk for a protein shake or smoothie is a perfectly fine (and delicious) way to incorporate some extra protein. You can also take a smoothie with you everywhere and sip it between meals for extra protein ingestion.
Although whey lends itself well to this kind of mixing, casein is going to create a much thicker drink.
It can be a good idea to incorporate casein into things like protein puddings.
When it comes down to it, the question of whey and casein is going to come down to the individual and their specific goals. These things mostly do, so there’s no one-size-fits-all recommendation.
However, if you’re even mildly serious about gaining lean muscle mass and you can afford it, doubling up on whey and casein is definitely the way to go.
However, this doesn't necessarily mean that the more supplements you take, the better off you’ll be.
You need to back up supplements with a proper and varied diet that hits all your macronutrient goals (including protein). And if you want to get your money's worth of protein powder, you need to be challenging your muscles regularly to elicit any growth.
There are no silver bullets to achieving the body and lifestyle you want—that’s going to come down to hard work. This goes without saying for most of us, but it’s important to not get lost in the weeds. Especially if you’re simply starting out in your fitness journey, debates between casein and whey are only going to distract you from the larger picture.
At the end of the day, you can supplement all you want with anything you want—or not at all—but it’s only going to be your own habits and convictions that get you to the finish line.
