When you have a new baby it is your job to keep their little belly full. You measure your success as a mom by how they gain weight. There is some kind of connection between mothering and food.
When they are toddlers you are still trying to make sure they eat the right stuff and enough of it.
When they reach 4 (or so) you begin to have this conversation...
"Sweetie, this is what's for dinner. This is what we are eating. If you are hungry, you will eat. You don't have to eat if you are not hungry. But, the kitchen is closed after dinner. There will be no snacks."
Then your child continues to turn up their nose at the food before him.
Then dinner is over.
Then it is time for bath and bed.
Then said child begins to whine. "I'm hungry! I want a snack!"
The mother-food connection in your brain starts to freak out. Oh my stars! My poor baby is going to starve to death. So you consider going back on your word. After all, the child is probably very hungry.
Then you pull yourself together.
"Honey, Mommy told you that when dinner was over there would be no more food. You chose not to eat and now it is time for bed."
Much weeping and wailing ensues. Mostly from the child but some from you as you sit in the other room and wish they didn't have to experience natural consequences.