from, "Food Rules: An Eater's Manual," by Michael Pollan
PART III: How Should I Eat? (Not too much.)
Rule #61 - Leave something on your plate.
Many of us were told by our parents while growing up that we should always clean our plates - an instruction that later in life we have perhaps taken a little too much to heart. But thee is an older and healthier tradition that holds it is more genteel not to finish every last morsel of food: "Leave something for Mr. Manners," some children once were told, or, "Better to go to waste than to waist." Practice not cleaning your plate; it will help you eat less in the short term and develop self-control in the long.
Eat food. Not too much. Mostly plants.