Most people are either too busy or too lazy to do some kind of exercise. Exercise shouldn't be viewed as a chore, it's as simple as riding a bike orplaying basketball or some other sport with your family. Another main reason is that unhealthy foods are often the cheapest you can find while healthy foodsare quite expensive in most areas. It's convenient and cheap to buy unhealthy food that is made up mostly of refined sugars and fats like 25 cent chips oran entire box of cookies for a dollar, and therefore people, especially young kids are more inclined to buy these kinds of food. It is mostly anindividual's fault for not taking care of themselves, but some of the blame has to fall on the government or the FDA. It is a difficult and complicatedproblem because the government can't just stop companies from making cheap food or from using cheap, potentially harmful ingredients and the governmentcan't stop people from eating these foods.
One of the worst problems is that even with increased awareness, multiple documentaries, and clear evidence, people just refuse to pay attention. For example,I remember a case where some girl tried to sue McDonalds because the food made her fat or something. Things like this are disappointing because instead oftrying to make a lifestyle change for the betterment of her life, she just decides to attempt to blame someone else. The documentary "Supersize me"was a decent documentary that revealed a lot of things, and yet people still continue to eat fast food in excess.
I doubt the problem will ever go away. On the contrary, it will most likely get worse with the addition of hormones and genetically modified plants andanimals. Pretty soon, food will be completely man made instead of being natural and who knows what kinds of consequences this will have on the population.