This, if food just gives minor buffs it might not be worth your inventory space. And if food gives major buffs then that is BS, again drugs would be a more sci-fi way to give major buffs.
The way you cook food should be a certain way that the more complex foods can make you sick if you make them wrong!!
Psh, food? I love food. I'd be all for it. Not sure how it would go down though. I like the idea of having different game-modes, as earlier stated, so people could choose to do it or not. If no food-bar, buffs would be the way to go for me. Like if you eat a jalapeno, steam comes off you and you run faster . If you eat raw/spoiled food, you get sick, hurting your energy bar. Some food could heal poisons, increase health, ect. I like the idea.
I would love cooking in the game, but I honestly don't think that you need to make it so it gives you a "buff" per se. I worked for a long time cooking in WoW once I heard that there were things that would temporarily change how your character looked, so it could be a minor distraction in the game. Like food that makes your character bigger the more of it you eat (damage, move speed, all stats stay the same, just cosmetic). Or have penguin bites that turn you into a penguin, or bat bites that gives you character bat wings. All of these effects are on a timer though, so your character wouldn't be 200ft tall forever, just 3 minutes or something.