13 and food...

Well, Ive seen her chew gum in Joy, but I cant really post a picture of her chewing gum haha.

In "Unfaithful" when she is in her apartment with Foreman (after he got fired). She walks over and sits beside him at the cozinha table, and has a bowl of something (cereal maybe)

In house divided she ate alcoholic ice cream and a breath mint to cover the smell of alcohol from the bachelor party.

I know this is really late but...She is seen eating in "Knight Fall" when her and Foreman went to that fair, In "The Dig" when she was talking to House in the motel room, in "Epic Fail" when she goes to House's apartment and House has her taste his cooking...That's all I can think of right now besides the other respostas already posted :)