High
Fructose
Corn
Syrup
It is not the entire problem, but it is a huge part of it.
Yep. One of the most powerful lobbies in Washington. That, and eating habits. I remember when "the fat kid" was a rarity in school, whereas now, it's the norm.
It's all the Facetubing and Youbooking, vidya games and TV. Kids can have fun without leaving the comfort of their chairs. Also, the tons of processed, cheap, unhealthy but convenient crap that people eat today contributes to the problem as well.
Yup. Horrible eating habits combined with a sedentary lifestyle have produced a deadly mix. While I do not favor regulating food to force people to eat better, I
do think we simply accept HFCS as a substitute for sugar when it has serious metabolic effects that are vastly different from how cane sugar works. And this is primarily done to benefit Midwestern corn farmers, who get nice subsidies for it.
Regardless of the effects on the farming industry, I believe we should phase out HFCS as a sweetener, and go to cane or beet sugar. If it skyrockets the price of soda, I couldn't really give a shit. People need to drink less of that anyway.
I am not the best eater in the world, living alone, but I do try to avoid the really awful stuff. My wife cooks every day for the kids, and they also play outside at least five days a week. The two oldest are 5 and 2 and neither has ever had any kind of weight problem. They also aren't allowed to drink soda, and junk food of any kind is a very rare treat.
I've had weight issues since I was a teenager, spurred on by various medications, and it's taken me a while to really get that under control and start getting it down. Well, actually, losing my job started me on getting my weight down.

But I have been sticking with that, trying to eat better and exercise more. I am otherwise healthy and don't really suffer any ill effects, but I'd rather not wait until I do in order to do something about it.
The cut-and-dried of this problem, however, is that the worst foods are cheap and ample. Eating right is expensive. Most people have no sense of portion control. And many things are marked as "reduced fat" or "low fat" in order to deceive people into thinking they are healthy--but all they did was replace the fat with calories!
The problem is manifold, but changes in business practices, government policies, and consumer attitudes would be necessary to fix it.