You can buy all kinds of protein powders: Egg, whey, casein, etc. Just make sure they don't have added sugar. If it were me, I'd just use raw eggs in a smoothie of some sort. Cheap!

One can always buy sugar-free syrups, unsweetened cocoa powders, a few berries, and make your own low carb flavors.

Very cool you were an exercise jockey! Sounds like an exciting thing.