dtgreene: How about the (rather simple) approach taken by Shiren the Wanderer (and many other Mystery Dungeon games):
* If your belly is not empty, you recover some of your health (about 1/150th of your max; I think this is the number Shiren uses) each turn.
* If your belly is empty, you instead lose health at that rate.
* Even a minor food item (like an herb) will give you 5 belly (enough for 50 turns), so using them when you've taken damage from hunger (rather than using them the instant you start starving) can be a way to conserve food.
(The situation could be interesting in something like Pokemon Mystery Dungeon, if say you have no food but do happen to know Leech Life, which you can use to keep yourself alive if you can find an enemy to use it on.)
Darvond: I found that mechanic aggravating due to RNG in the early mystery dungeon games, and pointless by the time PMD rolled around. As for Leech Life, it would be
neat if it worked that way, but Game Freak are often a brutally lazy and uncreative lot, so it doesn't. It and Leech Seed are just generic lifedrain movies.
Thing is, when you're constantly losing HP, any effect that can restore your HP will keep you alive longer; this includes Leech Life. Hence, if you can find enemies to absorb HP from, you can keep surviving for a while, at least until you run out of PP for that attack.
The one move I was disappointed in, actually, is the Transform ability; in the main games, I happen to like the move as it allows you access to moves the Pokemon would not normally get (along with moves like Mimic, Metronome, Mirror Move, and Sketch), but in the PMD games, it's useless. Furthermore, since it is the only move a certain Pokemon (Ditto) can ever learn, it makes Ditto useless. (Smeargle, on the onther hand, is *really* good; in PMD1, Smeargle can eventually be the most powerful Pokemon, and in PMD2, Smeargle is still one of the best (though maybe not as good as Drifloom/Drifblik who can attack twice per turn if not holding anything.)