They've done studies on this: the "endless bowl of soup" (people eat less if they have to actually eat bowl one then bowl two) or M&Ms either in a large bowl or in small individual packets (eat all you want with either, people eat less with individual packets).
Discussion
Works even better, if you serve the food from the kitchen, so that they have to get up and walk across the room, to get another portion.
Using laziness to lose weight. 💪🏻