It's kind of a crappy situation for many, many people--especially those in cities or urban areas with limited access to quality supermarkets. The number of supermarkets per 100,000 people in cities and low-SES areas is surprisingly fewer than in suburbs or more affluent areas of the city (in general).
Fruit and veggies don't sell in the cities because they are more expensive and more demanding (as far as preparation for a family) than walking into KFC and getting a bucket of chicken for the fam to share. Fast food moves in and good supermarkets move out. Or, if you walk into a city convenience store/supermarket--the selection of produce is usually more dismal than in your average suburban Super-Wal-Mart or Shaws or PathMark or whathaveyou.
I'm all for personal responsibility and I also tend to swing more libertarian than anything else--but there *is* a big element of this epidemic that is society-generated or at least propagated by the natural evolution of food companies financially (both supermarkets AND fast food joints).
I believe in a laissez-faire economy, which would accept the fact that supermarkets in cities have a right to make their produce section smaller than their chips/dip section, because it's a good business decision... And it would also accept the fact that McD's and Wendy's should be able to buy that vacant lot where the crack-house burned down and set up shop, because they will probably sell a lot of product there.
But, if NO ONE takes responsibility, it's an issue. Volunteer based organizations (or even for-profit ones), as well as health professionals, teachers, educators, etc, need to help the general public take their lives back--to empower people and give them the self-efficacy to make changes in the way that they--as individuals--conduct their lives.
Cuz at the end of the day, it doesn't matter who regulates what and which companies take "corporate responsibility"--we still live in a society where you can ALWAYS get that quarter pounder in the middle of the night, and chase it with a milkshake. The problem is with the individuals who make these bad choices to begin with.