One direction I think food could go is that you could combine 3-4 or so food items to create a Ration item, which would be consumed during a long rest - perhaps as a way of discouraging overuse of long rests. (Although it's not clear at this time if rations will be a thing in the game at all.)
That idea does have some problems though, as by the time you get to level 4-5 or so, you'll probably have more than enough money to purchase as many inn rests or as many Rations as you feel like carrying, and that mechanic limiting long rests slightly will be irrelevant.
I fear though, that food items might go the same way as they did in DoS 1/2 and function as ingredients for an overly elaborate recipe system no one actually uses, so you end up carting them around forever and never using them.
That's a really good point, it would be cool to try to figure out all the different ration recipes, similar to Dinners in DOS! We haven't seen any in-game crafting yet, but knowing how fun that system was in previous DOS games i would hope Larian wouldn't be afraid to integrate it into BG.
If they really wanted to do a buff system (though i personally don't much like them), they could differentiate certain special, rarer rations as well to give minor stat bonuses, like +1 to a skill or ability for the day (which would at least get rid of the weird "eat before combat" dynamic)
