Location, location, location. The closer you are to food, the more you eat -- sometimes twice as much. Don't linger at the buffet table; put a few hors d'oeuvres on your plate, then move to another part of the room.
Go slow. People tend to eat at the same pace as those around them, so match your speed to the slowest diner at the table. Better yet, try to be the last to finish your meal.
Outsmart the host. You might think that eating a big helping of your grandmother's stuffing shows her how much you enjoy it. But studies indicate that hosts remember the number of servings you have, not how much you eat. So next time, compliment Grandma by starting off with a small amount of stuffing (such as three or four tablespoons), then go back for seconds, sticking to the same-size portion.
Source: Brian Wansink, PhD, author of Mindless Eating: Why We Eat More Than We Think.