Food ATM always has +XP bonus on it, which is exactly what you don’t want if you are intent on levelling slowly and say exploring more than one area of the same level requirement (and maybe levelling a craft at the same time).
So why not have negative XP food that makes you gain experience more slowly? Such food would have a compensating bonus to make up for lack of XP gain, the best one I think being +Karma. So you might have food items with:
-20% XP bonus
+20% Karma gain
Maybe some other bonus – +magic find would be great.
I would love to see this kind of food available right out of the starting gate so I can do a couple of starter areas at the level for which they were designed.
And people! such food would be entirely optional – you rushers need not apply!