Whey Protein Explained

Not all whey is the same

Not all whey protein is created equal — if you want to actually understand what you're buying, here's what you need to know.

Whey is essentially the liquid left behind after casein is removed from milk. In simple terms, milk is deliberately curdled, which separates it into a solid part — casein, essentially curd cheese — and a liquid part, sometimes called milk serum, which is whey. This process gives you plain sweet whey, and on its own it's actually a poor choice for boosting your protein intake. Why? Because in this raw form it typically contains only around 12% protein and over 60% carbohydrate (lactose). You might have also heard the idea that dried whey could work as a cheap gainer (carb supplement). That's simply wrong. The protein-to-carb ratio might superficially resemble some gainers, but real gainers use maltodextrin and glucose as their carbohydrate source. Lactose, which in larger amounts causes unpleasant digestive issues for a lot of people, is only ever a minor component in decent gainers by comparison. Lactose just isn't a good carbohydrate source to rely on. But that's a bit of a tangent — back to whey itself.

How whey is processed

The first and most basic way to process whey is into whey protein concentrate (WPC). If you read the labels on protein products closely, you'll notice most of them are made from concentrate. Processed this way, whey ends up with a protein content anywhere from 25% to 90% of dry weight, depending on how much lactose has been removed. That's obviously a huge range, so keep in mind: the higher the protein content, the lower the lactose — and just as importantly, the lower the protein content, the more lactose you're getting. Worth remembering when shopping for a concentrate; aim for one with at least 65% protein as a realistic minimum.

Once the finished product exceeds 90% protein, you're looking at whey protein isolate (WPI). There are roughly three ways to produce it. The first is straightforward filtration. The second, which you might recognize from supplement advertising, is CFM — cross-flow microfiltration — where the whey is filtered through ceramic filters. The third method is ion exchange.

Hydrolyzed whey sits at the very top of the protein-supplement world. "Hydrolyzed" essentially means pre-digested, which for you as the consumer means the protein reaches your muscles faster than it would in another form. That makes it particularly useful right after training. There are different degrees of hydrolysis, and in my view, around 20% hydrolyzed whey protein in a product is more than enough — partly because a heavily hydrolyzed product is hard to make palatable (it tends to taste bitter), and partly because you won't meaningfully benefit from that much pre-digested protein hitting your system at once anyway. That's just my own take, and if you go looking online you'll almost certainly find other opinions — which, admittedly, is true of nearly everything.