Optimum Nutrition Whey Protein Isolates are 90 pure protein by weight. They are the purest & most expensive form of whey protein that exists. That rsquo s why they are the first ingredients you read on the 100 Whey Gold Standard label. By using Whey Protein Isolates as our primary protein source we rsquo re able to pack 24 grams of the purest muscle building protein per serving with a lot less of the fat cholesterol lactose & other stuff that you can do without.