Eating has always been rumored to lessen the chances of spell casting failure. Whether this is true or not is up for the judges to decide.
Another thing is that if someone has casted paralyze on you, and you eat while you are paralyzed, you theoretically should be able to start running immediately again after the spell wears off, though I could be in err on this one.
I'm pretty sure it's just a stamina regain, with a limit to how often you can do it in the form of "hunger."
In other words, paradoxically, not eating is probably better than eating, since if you really need to get some stamina back, you can eat as much as you need.
Someone tell me: in what era did keeping fed start increasing skill gain?