Great point! Eat until your body is satisfied. If there is still something on your plate, DON"T feel obligated to finish it!
If you keep on eating, you'll soon sigh again. Here's your second chance to stop eating. If you continue eating more, you'll then sigh a third time. And so on.
The proper time to stop eating is right after the first sigh. That's when your body has taken in all that it can handle.
I heard Linda Dano talk about this, and I instantly related to it. I practice it everyday, and it works.