No food or drinks in the bedroom is a generally good idea but it does depend heavily on the kid and the way food and private space is handled in the household generally - especially as they get to their teen years it might just lead to a secret stash of food kept in the bedroom that you don't know about at all (which may or may not be kept in a sanitary manner.) The rule that more or less worked for me was no *dishes* in the bedroom - a bottle of juice or a cookie or orange was fine, but nothing complicated enough that I'd have to remember to take the dishes out. (It still led to bits of cookie or orange peels occasionally lingering but that is far preferable to dirty plates, and it let me eat what/when I wanted but keep it to relatively tidy options in the bedroom.)