This is the #1 question I get about CarboRocket and 333. The main reason is that protein can be difficult to digest and causes gastro-intestinal issues with most people when consumed during training and racing. It can also be hard to choke down and you won't hydrate properly if you can't drink something during a race especially if it's hot out. Save the protein drink for afterwards, might I suggest our recovery drink, Rehab.  Adding protein to your sports drink is based on old, de-bunked research. That being said, CarboRocket contains 1,000 mg of the amino acid L-Glutamine per serving which is one of the most important components of protein and one of the main reasons you would want protein in a sports drink to begin with. 333 then adds 3000 mg BCAA's and additional L-Glutamine per serving providing you with the benefits of protein without the drawbacks.