Huge chunk of meat
Eating a huge chunk of meat will likely make you oversatiated unless you were fainting beforehand; beware eating anything if you are oversatiated, as you are very likely to choke over your food and die unless you are wearing an amulet of life saving or are breathless. The huge gain in nutrition will keep you satiated for at least a few hundred turns, which abuses dexterity; be prepared to exercise enough to potentially offset the stat abuse, or else have a way to fix lowered stats.
Healers in particular always start with a spellbook of stone to flesh, which allows them to easily make and live off huge chunks of meat as long as they are able to find boulders; at the least, it will last them long enough to find some permanent sources of food, and provides a "buffer" for nutrition drain from spellcasting.
- See the encyclopedia entry for meatball.