I liked the way World of Warcraft handled food. First, they made it fun by giving you a "cooking" skill that you could level up, learning additional recipes and working with more advanced raw materials (this was tied into fishing in a nice way). They didn't take it as far as they should have, but it was a good seed idea. What I liked was that your character never died of starvation or the like; it's just that eating certain foods would give you temporary stat bonuses and speed up your hit point recovery. Thus, you could keep your character "well fed" for that extra edge, but it wasn't necessary for survival. Drinking water was only necessary for magic-users who need to quickly recover their mana points. Again, characters aren't dying of thirst, but only drinking to speed up a process.

I wouldn't be opposed to using food in other games, and perhaps the idea could be extended to other areas. Perhaps a light source isn't essential in a dungeon, but maybe having good lighting would boost your ability to hit monsters and reduce your chances of being surprised.

I'm trying to think of how age could apply and coming up short. It seems like the leveling process is already a type of "aging." The bulk of this seems to be pushing towards making older characters less desirable to play--and can anything imagine how that could be fun? One of the biggest rewards of any RPG is seeing your characters grow and become more powerful. A punishing aging system would just impair that.

Let's put it this way--if your RPG had an option you could turn on and off for gradually aging your characters and reducing their stats, who would play with it on? I know I'd pop that thing off the second I knew it existed.