I don’t know what you’re talking about. The bionic prepper has a plastic canteen. That works nicely.
Have you heard of “Pemmican”? Neither had I, but it’s even better than a granola bar.
Pemmican sounds better than MREs to me, but maybe the military has a reason to have remarkably terrible food(from what I’ve read).
In any case, you are aware that the game starts five days after the Cataclysm began? You probably did have food, earlier.
As best as I can tell, none of the professions start with food. I’d assume the survivor ate that between going to the shelter and the start of the game. That’s just my guess though.