What if a vampire eats food but doesn’t have the Eat Food Merit?
A vampire may consume food, but it refuses to stay down — unless the vampire spends a Willpower point each turn, she vomits within the scene (though some Storytellers may allow players to spend a point of Willpower to keep a character from vomiting).
The same rules apply for drinking, as well. Note that other vampires find the practice of eating mortal food utterly disgusting — “like eating a pig’s slop,” in the words of one rural Gangrel — and one who makes a practice of doing so will probably earn the derision of his undead peers.