Both milk protein and whey protein isolate are great sources of protein, but there are some key differences that are important to study up on before you start consuming. To help, we’re going to compare milk protein isolate vs. whey protein isolate. But first, what even are these things? Basically they are just protein powder — the kind of stuff you see people add to protein shakes and smoothies - but milk protein isolate has more casein than whey protein isolate. We'll explain more why that matters.
Milk Protein Isolate
They say the healthiest foods are the ones that contain familiar ingredients — no weird stuff like “butylated hydroxytoluene” and “partially hydrogenated oil.” So when you see “milk protein isolate” on a label, you might be like “umm pass.” But milk protein isolate is actually a natural and healthy ingredient.
Milk protein isolate is essentially powdered milk; it’s a way to get the same protein you would find in cow’s milk into things like health food bars (e.g. Rez Bar) without actually using fresh milk.
There are two proteins in milk: casein and whey. With milk protein isolate, you are going to get both of these proteins, but just as you would in whole milk, you’re getting a higher percentage of casein than whey (hang tight and we'll explain what this means later).
People who can’t drink milk or have dairy products can have milk protein isolate because lactose is removed from the milk, according to Live Strong. What’s left is a pretty much pure protein and amino acids. “Milk protein isolate's total protein content is at least 90 percent with less than 3 percent fat, very few carbohydrates and almost no lactose, making it suitable for most people who suffer from lactose intolerance,” writes Live Strong.
Whey Protein Isolate
Whey protein isolate is another type of powdered milk product (usually flavored) used to give smoothies, shakes and health bars a protein boost. But while milk protein isolate is made from whole milk, whey protein isolate is made from just the whey — go figure. Whey is the watery part of the milk that separates from the creamy part (think about that liquid layer on top of yogurt). It’s a byproduct of cheese. According to Healthline, whey protein isolate is also about 90 percent protein. It also contains a bit of fat and carbohydrates. According to Healthline, whey products are used primarily to build muscle.
Milk Protein Isolate vs. Whey Protein Isolate
So what’s the difference between the two and why do Rez Bars use milk protein isolate vs whey protein isolate?
According to the American Dairy Products Institute (yes, that’s a thing), the differences really all come down to that pesky casein and whey.
“Though you can buy either ingredient and get the same amount of protein, this is where the similarities end. Though it may be tempting for product developers to substitute one or the other based on which one is lower in cost, they will find that in many cases it is not an easy substitution. The source of the differences starts with the basic structural differences between caseins and whey proteins,” they write.
“When compared to casein, the evidence is more mixed. Whey appears to be effective in the short-term, but casein stimulates muscle growth over a longer period, making the net effect similar,” Healthline explains.
So, they are similar, but If you’re looking to lose weight or curb cravings, casein is the protein for you. According to Live Strong, “as a ‘slow-acting’ protein, casein is more satiating than whey in the long term, which can help with controlling hunger and cravings.” And by “slow acting” they mean that the body digests casein slowly. Furthermore, studies suggest consuming both casein and whey together has optimal weight loss effects, meaning as between milk protein isolate vs whey protein isolate, milk protein isolate is the winner here because it contains both proteins.
“Both whey and casein offer all the essential amino acids necessary for muscle growth in a highly digestible form,” writes Live Strong.
As we mentioned, milk protein isolate is slowly digested, while whey protein isolate can be digested faster. This means that for long-term lifestyle, milk protein isolate is a better choice. However, if you’re on the go and want to chug a protein shake after a workout, whey protein isolate is easier to digest. Also, whey protein isolate contains some carbs and fat, which is good if you plan on burning that off for energy.
Whey protein is often popular among bodybuilders and those hitting the gym regularly. But if you’re gaming and sitting down for long periods of time, you’ll want a protein that contains little to know fat or carbs like milk protein isolate.
And this is why in the matchup between milk protein isolate vs whey protein isolate, Rez Bars go with the all-mighty milk protein isolate.