“Not for many, many years. Taste may go off a bit, but unless you got a broken seal or botulism, canned food stays edible for decades.”
Not true. 3-5 years is safe. Maybe a little longer for frozen. Eating decades old canned meats is very risky. Definitely not a good game plan when there are options to use ahead of time.
Carbs and proteins are the forms of calories that store well long-term (decades ranges). Need to remove oxygen and control temperatures. You can also get calories from alcohol which is like carbs. Alcohol stores very well.
Fats and oils go rancid over time no matter how you store them. Partially hydrogenated oils (like Crisco) aren’t good for you but do have a long shelf life, so that’s a reasonable compromise when facing life-threatening famine.
As I said, unless there is botulism in the can, or the can’s seal is broken, it is quite safe to eat even years after the “use best by date”. That is not an “expiration date” like they put on the milk carton, it is just the date at which the company has determined the flavor of the canned food will begin to noticeably decline. Meats will still be edible for years, even decades after that date, as many experiments have shown.
As for fat going rancid, yes, it happens, which is one of the main reasons the flavor goes “off”. But though rancid fat tastes bad, it is not dangerous to eat, though it can give you a stomach ache or some issue like that.