There's so much food in the game, as relatively new player it seems to me there must have been bigger plans for this by blizzard at some point. I am constantly trying to sort through ingredients only for their value in training me to the next cooking level, and vendoring or even trashing the product. With fish I often don't even bother on some classes, the food fish just get tossed instantly. A free bag slot is more valuable than an extra stack of food most of the time. Sure my warrior alt eats more than my warlock, but even so it's just so abundant I never worry about running out, the only food concern is how to carry it all while collecting maximum loot.
What I'd propose is a glyph/challenge that primarily adds a simple hunger meter. When meter depleted:
- cannot run (ie you must RP walk)
- cannot mount
- cannot regen hp/mp normally (healing spells and potions etc still fine)
- cannot receive rested xp (maybe even drop xp to unrested turtle mode rate, or off entirely)
- all debuffs last double duration
- increased mob aggro range equivalent to player 7 levels lower
- some value towards hunger is assigned to each food item, separate from existing food functions
- Eating same food over and over should have diminishing returns for satisfying hunger ie carry one stack only and you'll have to eat more to fill your hunger meter than if you had multiple different kinds of food
- Existing food items should be assigned duration that applies only to items in glyph player's inventory/bank; some can be permanent but only replenish hunger in small amounts, others spoil (disappear) quickly but fill you up in just one or two items.
- All food and ingredients carried in glyph players bags is destroyed on death (or make it lootable by self and other glyph players -- might be fun to steal enemy food when pvp'ing with this glyph)
As described here so far, this probably wouldn't really be a difficult challenge, just add some thematic purpose to having such absurd abundance of food in the game. Optionally maybe could additionally restrict these players from trading food items with any non-glyph player and on AH, would make it a little more challenging -- with such a restriction the difficulty will come down to how quickly food (& maybe ingredients too) are set to spoil/disappear.