Actually? In the USA the problem is that healthy balanced diets are not taught to kids. Greens are Yucky! Is as bad as "Maths is Hard!". We teach and enable a diet of bad eating.
Remember a big mac is fine, the calories come from the gigantic coke and the oil laden fries. We need that sort of education in schools. Not abstinence from junk food but to realise that junk food is like a Michael Bay movie. Too much and it is bad for you. But sometimes what you really want is a Big Mac.
In addition it seems like the USA has very little casual sport. Unless you are Chuck Beefsteak, Star Quarterback... you aren't going to get any exercise. In fact sports seems to be linked with obesity in the USA as most stadiums sell insanely huge portions of food and watching it is accompanied by food too.
There is nothing wrong with butter, there is nothing wrong with sugar, it is the quantity we eat it in.
I grew up in a place where I did a lot of exercise. After I picked up my job I stopped. It's rather hard to exercise after a 12 hour shift when you just want to sleep. So my weight spiked. And now it's actually hard to start up again. If we inculcate a habit as a kid and make it a family event we will see a drop.
The problem is in the USA is that parents often spend little time with their kids. Right now? If I had a kid I think that kid would never see his father except at bedtime and mornings. What that kid needs is a little outside time everyday where EVERYONE exercises. Dad goes for a jog, kid watches. Dad kicks a ball around after. Kid slowly joins him on jogs (I say dad when I mean any parent!).
I think the Chinese and Cubans have it right. Rather than deal with obesity as a end we should prevent it. Make socialising and exercise a thing. Improve eating habits.
Exercise alone won't let you lose weight. I mean a short jog only removes a hundred or so calories. You need to change how we eat and reduce quantities. And this means across the western world we need to improve diets.
I am with Jamie Oliver on this one. I think everyone should learn to cook and learn to cook healthy AND unhealthy so that they know when to do which. Part of my problem is that I do not cook here so I end up eating hospital food which is rather bad for you. High grease, high starch. Perfect for starving people in India, not so good if you get 3 meals a day!