Whey Protein Isolates are 90% pure protein by weight. They are the purest and most expensive form of whey protein that exists. That s why they are the first ingredients you read on the Gold Standard 100% Whey label. By using Whey Protein Isolates as our primary protein source, we re able to pack 24 grams of the purest, muscle-building protein per serving, with a lot less of the fat, cholesterol, lactose, and other stuff that you can do without. There s no question this is the standard by which other whey proteins are measured.