Despite the plethora of protein powders on the market nowadays, most folks opt for whey or casein.

There’s a good reason for this: experts and studies almost unanimously agree they’re the most effective protein supplements for supporting muscle growth.

There’s less consensus, however, when it comes to which of these two is best.

Some say whey is the best protein for building muscle because it causes a rapid spike in amino acid levels in the blood (the “building blocks” of protein), which helps you build muscle faster.

Others claim casein is the real winner because it’s a “slower-burning” protein, keeping your amino acid levels elevated for much longer than whey, which leads to more muscle growth over time. 

Who’s right?

In this article, we’re going to look at what science says about the merits of casein vs. whey protein, so you can decide which is best for you.

What Are Casein and Whey Protein Powder?

Cow’s milk contains two types of protein: casein and whey (80% casein and 20% whey).

Supplement manufacturers extract both of these proteins and process them into powder which they sell as protein supplements.

Both are popular among weightlifters because they contain all the essential amino acids (amino acids your body must get from food), and they’re rich in the amino acid leucine, which plays a vital role in initiating muscle protein synthesis (MPS).

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What’s the Difference Between Whey and Casein?

The main difference between whey and casein is digestion speed. 

Whey is acid-soluble (it dissolves in acid), so it digests quickly in your stomach. This means it spikes blood amino acid levels soon after you consume it, stimulating a rapid increase in MPS (especially when you take it post-exercise).

When casein reaches your stomach, it curdles in the acid, slowing its digestion. As a result, casein doesn’t elevate blood amino acid levels as high as whey protein, but it keeps them elevated for longer (up to six hours).

Here’s a graph illustrating this point:

Leucine Appearance

Many people make a big deal of this difference, claiming whey is a better post-workout protein because it expedites the muscle-building process, and casein is a superior pre-bed protein because its “slow release” prevents muscle breakdown during the hours that you’re asleep (and thus not consuming protein).

While this logic seems reasonable, research doesn’t support it.

Studies show that both types of protein aid muscle growth equally well, and provided you consume enough total protein throughout the day, taking casein before bed offers no benefit.

(And if you’d like specific advice about how much protein you should eat to reach your fitness goals, take the Legion Diet Quiz.)

In terms of taste and texture, whey and casein are quite different. Whey tends to have a lighter, more refreshing flavor and mouthfeel. In contrast, casein tends to be thicker and creamier (which is why people often use it in high-protein puddings, pancakes, and other recipes).

There are also a handful of minor health benefits associated with both whey and casein. 

Casein contains compounds that may reduce high blood pressure, lower cardiovascular disease risk, and act as antioxidants. Whey contains antibodies that exert antioxidant effects and enhance nutrient absorption. That said, none of these benefits are significant enough that they should sway your opinion one way or another. 

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Casein Protein vs. Whey Protein: Which Is better?

Casein vs. Whey for Muscle Building

As we’ve already seen, whey and casein have almost the same impact on your ability to build muscle despite digesting at different rates. As such, you shouldn’t tie yourself in knots trying to decide between the two—go with whatever suits your preferences. 

Personally, I like drinking a shake made with Whey+ protein isolate after training because it’s light and refreshing, which is more fitting after a hard workout than heavier, creamier casein.

Casein vs. Whey for Weight Loss

No kind of protein powder will directly burn body fat or help you lose weight on its own.

That said, research shows that casein may help increase fat loss slightly more than whey protein when combined with a calorie-restricted diet.

If you want a clean, 100% natural, delicious micellar casein protein powder that’s naturally sweetened and flavored and contains no artificial dyes or other chemical junk, try Casein+

(And if you aren’t sure if Whey+ protein powder or Casein+ protein powder is right for you, take the Legion Supplement Finder Quiz! In less than a minute, it’ll tell you exactly what supplements are right for you. Click here to check it out.)

FAQ #1: Is it worth buying a casein whey blend?

It depends.

If you can find a casein and whey blend that provides high-quality casein and whey from hormone- and antibiotic-free cows, that also contains no artificial food dyes, junk additives, fillers, soy, gluten, GMOs, MSG, or hormones, and that’s 100% naturally sweetened and flavored, it could be a viable option.

If, however, buying a casein and whey blend means you have to opt for a protein supplement of lower overall quality, it isn’t worth it. Go for a premium casein or whey protein powder, such as Whey+ or Casein+ instead.

FAQ #2: Is casein or whey better for women?

Both are about as effective as each other for helping women build muscle, so choose whichever suits your personal preferences.

FAQ #3: Is whey or casein suitable for vegans?


If you’d like a vegan protein powder that’s about as effective as whey or casein for building muscle, try Plant+.

+ Scientific References