*“It seems to me that our three basic needs, for food and security and love, are so mixed and mingled and entwined that we cannot straightly think of one without the others.” *

- M.F.K. Fisher

Human beings are notoriously terrible at knowing when we're no longer hungry. Instead of listening to our stomach - a very stretchy container - we rely on all sorts of external cues, from the circumference of the dinner plate to the dining habits of those around us. If the serving size is twice as large (and American serving sizes have grown 40 percent in the last 25 years), we’ll still polish it off. And then we'll go have dessert.

Consider a clever study done by Brian Wansink, a professor of marketing at Cornell. He used a bottomless bowl of soup - there was a secret tube that kept on refilling the bowl with soup from below - to demonstrate that how much people eat is largely dependent on how much you give them. The group with the bottomless bowl ended up consuming nearly 70 percent more than the group with normal bowls. What's worse, nobody even noticed that they'd just slurped far more soup than normal.

Or look at this study, done in 2006 by psychologists at the University of Pennsylvania. One day, they left out a bowl of chocolate M&M's in an upscale apartment building. Next to the bowl was a small scoop. The following day, they refilled the bowl with M&M’s but placed a much larger scoop beside it. The result would not surprise anyone who has ever finished a Big Gulp soda or a supersized serving of McDonald’s fries: when the scoop size was increased, people took 66 percent more M&M’s. Of course, they could have taken just as many candies on the first day; they simply would have had to take a few more scoops. But just as larger serving sizes cause us to eat more, the larger scoop made the residents more gluttonous.

Serving size isn't the only variable influencing how much we consume. As M.F.K. Fisher noted, eating is a social activity, intermingled with many of our deeper yearnings and instincts. And this leads me to a new paper by David Dubois, Derek Ruckner and Adam Galinsky, psychologists at HEC Paris and the Kellogg School of Management. The question they wanted to answer is why people opt for bigger serving sizes. If we know that we're going to have a tough time not eating all those French fries, then why do we insist on ordering them? What drives us to supersize?

The hypothesis of Galinsky, et. al. is that supersizing is a subtle marker of social status. Here are the researchers:

The act of choosing a speciﬁc size within a set of hierarchically arranged options is one avenue by which individuals signal to others their relative rank in a social hierarchy. As a consequence, larger options would be selected by consumers, not merely out of a functional need for hunger but due to a desire to signal status.

This isn't such a strange conjecture. Think, for instance, of the alpha males in those David Attenborough specials on television - the most powerful animal is the one who eats the most, getting access to the felled antelope before anyone else. Or think of all the cultural norms that associate larger products with increased status, from the screen size of televisions to the square footage of houses. In category after category, bigger isn't just better - it's also far more prestigious, a signal that we can afford to splurge on spare rooms we'll never use.

To test whether this same principle applies to food, the psychologists ran a number of simple experiments. In one study, the demonstrated that subjects perceived those with a larger coffee as having more status than someone who chose medium or small, even when the price was the same. (The effect also applied to pizzas and smoothies.) In a second experiment, subjects were randomly assigned to "power" or "powerless" conditions, in which they were told to recall an experience "in which you had power over another individual" or "another individual had power over you." It turned out that those in the powerless conditions were twice as likely to choose the biggest size of smoothie (with more than double the calories) as those in the powerful or control conditions. (Those primed with power preferred the smallest size.) This same pattern held with bagels, even when prices were constant: those in the powerless condition chose bigger bagel pieces and consumed about 30 percent more calories than those in the power condition.

Needless to say, this paper captures a tragic dynamic behind overeating. It appears that one of the factors causing us to consume too much food is a lack of social status, as we try to elevate ourselves by supersizing meals. Unfortunately, this only leads to rampant weight gain which, as the researchers note, "jeopardizes future rank through the accompanying stigma of being overweight." In other words, it's a sad feedback loop of obesity, a downward spiral of bigger serving sizes that diminish the very status we're trying to increase.

But there is hope for our expanding waistlines. When powerless participants were first told that smaller hors d’oeuvres were served at more prestigious events, the psychologists were able to reverse the effect. Although powerless participants initially consumed 30 more calories than others - they tried to compensate for their lack of status by eating more - learning about the prestige of small appetizers led them to eat 25 less calories than those primed with power. “Understanding and monitoring the size-to-status relationship of food options within an assortment is an important tool at the disposal of policy makers to effectively fight against overconsumption,” the scientists write.

The larger point is that we don't just eat to fill the void in our belly. Instead, we eat excessively to fill all sorts of empty spots, one of which is a chronic lack of status.