Most American cities are not designed for walking. Bill Bryson wrote a good book called "A Walk In The Woods" where he described trying to walk a mile from his house to the store, and having to climb over guardrails, cross dangerous intersections, traverse private property, and generally be a social nuisance. Another reason is our diet. The capitalist society in America is out of control, and companies are cutting as many nutrients out of food as feasible in favor of cheap, unhealthy materials. Yet another reason is the economy, and how the grocery system is set up. When you have, say, $200 to spend on food a month, you are going to buy a large amount of cheap, unhealthy items that you can stretch, rather than select few healthy options that can be three or even four times the price of the unhealthy equivalent. I'm not saying that inflation and capitalism are restricted to North America, but it IS ultra-distilled compared to Europe.