Hello there!
Things that may give you cues about to stop and start eating would be a feeling of hunger.
You can tell when you are hungry, because of the way you're stomach may act. It may "grumble" or make some sort of noise and you know you're hungry, and need food.
Something that would give you a cue you are no longer hungry, would be a feeling of fullness, or a feeling you don't feel like eating anymore.
I hope this helps you!
~Galexie