In addition, according to a paper by several Northwestern psychologists (including my high school classmate Adam Galinsky), people often choose a larger serving size as a means to try to increase their social status, apparently oblivious to the resulting weight gain that ensues. The good news is that when subjects were nudged by being told that a smaller portion was more "prestigious," they responded by eating less.
So it turns out we don't just eat because we are hungry, but "we eat excessively to fill all sorts of empty spots, one of which is chronic lack of status."
That idea brings to mind Townes Van Zandt (”Townes Van Zandt is the best songwriter in the whole world and I'll stand on Bob Dylan's coffee table in my cowboy boots and say that.”-- Steve Earle) from "To Live is to Fly":
"We all got holes to fill, and them holes are all that's real;
Some fall on you like a storm, sometimes you dig your own."