As Americans, we eat too much, and still want more. Food is readily available 24 hours a day. We get patted on the back for working more hours. There are so many things in our culture that are not condusive to a healthy lifestyle, that we can't just blame the food.
Most of the food thats bad are microwaveable foods, and fast foods. If everybody cooked at home, we probably wouldn't be having these discussions about the poor quality of foods.