Whey protein on its own is good — but whey combined with casein is best for muscle size and strength gains.

What’s the best protein powder for gaining muscle and staying lean? This might be the #1 most asked question on the internet, but unfortunately, many times the wrong answer is given.

If someone says point blank, “Whey protein,” it means they haven’t looked closely enough at the science.

To be fair, Whey Protein Isolate (WPI) is never a bad option. Whey is one of the highest quality and most anabolic proteins on the planet. But in terms of protein powders, a 100% whey product is not as effective for gaining and preserving muscle mass as a protein blend that combines whey with casein, another daily protein.

This is not just my opinion: The research backs up.

Why Protein Blends Are Better Than Whey Only

Numerous studies confirm that combining whey and casein proteins (micellar casein in particular) is more effective for muscle growth than just taking whey protein alone. That's why I created Pro JYM in the first place.

The reason for this has to do with the rate at which the two proteins are absorbed in the body: whey is a very fast-absorbing protein, and casein is extremely slow.

One of the first studies to confirm this came from Baylor University in Texas. Researchers discovered that trained male subjects following a 10-week lifting program while taking a whey/casein blend after workouts gained 4 pounds of lean muscle mass while showing a slight decrease in body fat. Another group of subjects followed the same training program, but instead of taking a protein blend, they took a protein powder that only contained whey. This group gained zero muscle mass over the 10 weeks while gaining a small amount of body fat.

Those results were eye-opening: gaining muscle and losing body fat (protein blend) versus not gaining muscle and adding body fat (whey only). Protein blend for the win!

Casein Protein: The Key To Sustained Muscle Protein Synthesis

Another study, this one from the Mayo Clinic in Minnesota, found that the reason adding casein to whey is better for muscle growth was likely due to what I mentioned above about the different digestion and absorption rates — whey being fast and casein being slow)

Whey delivers its amino acids to the muscles very rapidly, which spikes muscle protein synthesis (MPS), the metabolic process behind muscle growth. This a good thing, of course, but there’s also a downside to whey’s speed of absorption: The amino acids are taken up quickly by the muscles, but then protein synthesis falls off a cliff.

Casein to the rescue! Because it’s absorbed so slowly in the body, amino acids are still trickling into the muscles long after whey’s supply has run dry. In the Mayo Clinic study, amino acid retention was considerably higher four hours post-workout with the whey/casein blend than with whey alone. This is hugely important because it means the anabolic response initially triggered by whey can keep going, thanks to casein. The longer the anabolic window is open, the greater the potential for muscle growth.

Think of a protein blend powder like a pitching staff in baseball. Would you rather have only one pitcher to rely on in a 9-inning game, or multiple? You’d want more than one because each pitcher brings something different to the table. The only issue with the pitcher analogy is that whey protein is short-lived like a closer, whereas casein is longer lasting like a starter. So it’s the opposite order from baseball — whey goes first and doesn’t last long, then casein takes over and goes the distance.

How to Pick the Best Protein Powder

Remember what the Baylor study showed? Subjects taking a blend of whey and casein gained muscle mass and dropped body fat; those taking only whey didn’t gain muscle and added fat.

Yet for some reason, many protein powders on the market contain only whey protein — you’ve probably noticed this when shopping for supplements. If you see “100% whey” on the label, or the product is simply called “Whey Protein,” “Whey Protein Isolate,” or “Whey Protein Concentrate,” you know it only contains fast-digesting whey.

My award-winning Pro JYM protein powder is different. It contains roughly equal amounts of three different protein sources: Whey Protein Isolate, Micellar Casein, and Milk Protein Isolate (which contains both whey and casein).

The Best Times to Take Pro JYM

Because the combination of whey and casein peaks MPS quickly and sustains it for hours, Pro JYM is the ideal protein powder to take around workouts when your muscles need a consistent inflow of amino acids.

I recommend taking 1 scoop of Pro JYM before workouts, and 1-2 scoops after training.

Another great time to take Pro JYM is before bedtime for those who want to truly maximize muscle mass. Casein shines here, providing a steady trickle of amino acids while you sleep, a time when your body might otherwise enter a catabolic (muscle wasting) state.

Pro JYM is also the best-tasting protein powder you can find, so you're getting amazing flavor to go with the results... win-win!


  1. Kerksick, C. M., et al. The effect of protein and amino acid supplementation in performance and training adaptations during ten weeks of resistance training. Journal of Strength and Conditioning Research 20(3), 643–653, 2006.
  2. Soop, M., et al. Coingestion of whey protein and casein in a mixed meal: demonstration of a more sustained anabolic effect of casein. Am J Physiol Endocrinol Metab. 303(1):E152-62, 2012.

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