No nationwide emphasis on fitness. No political points for taking on that issue? Not sure, but its definitely a problem.
Duh, yes. Because eating habits are very poor. There are too many bad choices shoved in everyone's face every day. The food industry has evolved into an entity that uses carbs, sugar, fat and salt to create foods that taste unbelievably good but are horrific nutritionally. While I think the Atkins diet is complete trash, one thing advocates have correct is Americans eat too many cheap carbs. They are processed to create delicious, addictive foods that people can't get enough of. These bad choices didn't exist 100 years ago, barely 50 years ago. Beginning in the 70s and 80s, things started really going downhill.
we eat way too unhealthy and have gimmick weight loss programs that dominate the market when the principle (for most people) is pretty straight forward. Expend more calories than you consume to lose weight...
You can't believe how many people completely ignore that principle or flat out live in denial thinking that there is some superfood/supervitamin that helps precipitate weight loss all the while letting them eat as much as they want. People are just flat out not willing to give up eating.
americans have poor eating habits and a sedentary lifestyle compounded by a need for instant gratification with minimal effort.
The increasingly sedentary lifestyle is also a part of the problem, no doubt. But I place the vast majority of the blame on diet. If people ate like they did 50 years ago and were sedentary like now, there would not have been an obesity explosion. Regarding your other post, the diet industry is the biggest sham in the history of mankind. People go from one bogus "diet" to another to another to another to another spending billions of dollars for nothing. The diet industry is the modern version of snake oil salesman from years past, except they are MUCH more successful.
It's a little like the 50% divorce rate, in that if you analyze it by age, education, race, income and even different regions or cities you get starkly different pictures.
Fast food, pre-processed food, TV / TV advertising, urban sprawl, portion sizes, long working hours. Personally if I had to pick one reason, it'd be the working hours. As people squeeze more working time in a day, self-prepared food becomes less appealing.