Ah, come on, it wasn't needed to re-start (except if you want to found more secrets or check every pit, or make right map. Do you know about secret right in the start room?
. There _is_ food respawn, in most snail groups (and there are more than one. And there are better respawning meat-monsters down below). But yes, game is worse in this aspect than LoG2.
Tab is stranger though. Are you sure that you didn't mess something in the options?