Clean the Plate Club!

Especially when I have only one meal planned for the day, I tend to overeat during that meal.
Or, at a restaurant I often eat whatever is put in front of me.
Fortunately, that stuffed, overeaten feeling is getting intolerable to me. I’m beginning to hate it!
But, during the meal I haven’t found the right thoughts to get me to stop eating before the plate is empty and before the uncomfortable fullness feeling arrives.
What strategies, and thoughts, would you suggest?
Much appreciated.