Stop after each bite - put your fork/spoon down and chew your food completely
Check in with your body - especially your stomach sensations
Ask yourself : Am I still physically hungry? - If yes, take another bite. Eat mindfully.
When you stop, check in with yourself. Notice what it's like to stop perhaps before you've cleaned your plate. What do you think about? Does wasting food cross your mind? Could the serving size be different next time? Allow yourself to sit with your thoughts for a moment.
Test your hunger boundaries using physical cues, in this way we can better tune into the messages from the body what it really needs/wants.