Re: When do you start refusing food?
We only eat at mealtimes and set snack times around here. They are allowed to eat as much as they want at mealtimes--only of the foods that are being offered and they are all healthy. But we don't do random snacking.
If they are complaining and I think they are bored and not hungry, I will offer something that they don't like. If they are hungry, they will eat it. If not, they will wait and stop complaining.