I once heard someone say "The child determins how much they eat. You determine what they eat." Made sense to me. Eventually the child learns that if I refuse to eat what I'm given, I'll be offered what I want. Same learned behaviour as tantrums to get what they want.

Works in the classroom at school too. If a student wants my attention and calls out for it and I choose to ignore it the first time, then I have to ignore it every time or they know the next time that it is only a matter of time before they get the response they want.