All of the parent's comments are seeming to point toward one fact: refined sugars are simply bad for you. I did read, on Slashdot I believe, how rats had the desire to eat more after they ate high fructose corn syrup --it wasn't the case for corn syrup, only HFCS.
IIRC, the USA is the only country where our soda/pop have HFCS as the sweetener and not cane sugar. HFCS is in almost every processed food from bread to coffee creamer.
If you're in a poorer neighborhood, it's likely you don't have access to a standard grocery. I heard Whole Foods is tying to make a push into poorer neighborhoods in order to introduce healthier foods. They're starting in Detroit and I wish them success. If obese people don't get access to proper nutrition, then they're only going to make health care more expensive for those that do take care of themselves.