Even if the popcorn is stale...  

My girlfriend and I have a running argument about the food (especially fast food) industry's complicity in Americans' massive weight gain of the past two decades. I usually come down on the side of blaming big corporations and the capitalist system (big surprise there) and she's a little more circumspect - and of course there's always a bit of subtext revolving around my own weight, which of course fuels the argument on my side etc etc. But in any case, this will help the cause:

Traditionally, the prescription for shedding extra pounds has been a sensible diet and increased exercise. Losing weight has been viewed as a matter of personal responsibility, a private battle between dieters and their bathroom scales.

But a growing number of studies suggests that while willpower obviously plays a role people do not gorge themselves solely because they lack self-control.

Rather, social scientists are finding, a host of environmental factors — among them, portion size, price, advertising, the availability of food and the number of food choices presented — can influence the amount the average person consumes.

"Researchers have underestimated the powerful importance of the local environment on eating," said Dr. Paul Rozin, a professor of psychology at the University of Pennsylvania, who studies food preferences.

Give moviegoers an extra-large tub of popcorn instead of a container one size smaller and they will eat 45 to 50 percent more, as Dr. Brian Wansink, a professor of nutritional science and marketing at the University of Illinois, showed in one experiment. Even if the popcorn is stale, they will still eat 40 to 45 percent more.

Keep a tabletop in the office stocked with cookies and candy, and people will nibble their way through the workday, even if they are not hungry. Reduce prices or offer four-course meals instead of single tasty entrees, and diners will increase their consumption.

More seriously, I've always been a little bit skeptical of arguments that take responsibility away from individuals for their own actions, call me an existentialist, I don't know. I remember years ago being totally flabberghasted by the way the big tobacco was crucified for basically letting people handle their own affairs - I wanted to start smoking as protest even. But it seems to me now that responsibility is a more complex animal, especially when there's an assymetry of consequences ie when corporations have incentives to create a less healthy environment for individuals and don't have to face any consequences. It will be interesting to see how these data are interpreted, and whether liability will become an issue. It's good to see companies like Kraft taking steps to change their approach, and I think inasmuch as the big tobacco lawsuits created an atmosphere where this kind of responsibility is on the radar screen, I think they must have been a success.