I am going to give my own thoughts based on some common sense mixed with a little education.
Honesly people, America is the laziest country. I believe that we are all more unhealthy and overweight overall than Japan for a couple of reasons.
First, if you're ever met anyone who is native Japanese, you'll find out quickly that they wake early and do not stop moving/working till bedtime. Its unheard of to just sit around as we do. They may eat a lot of rice, but they use it before its stored as fat. They also eat a LOT of veggies and little sweets, very unlike us Americans. We eat a combo of high fat and high carb diet and do pretty much nothing. Most of what Americans eat are "convience" foods. These foods are processed as well as contain lots grain sugars in addition to wheat sugars. We tend to also eat too much and they don't. We come from a society of more is better. Those of us who actually have a carb addiction, get into the craving/eat/low energy/craving/eat/low energy loop that is just so miserable and deadly. Then we remain unactive, sick, and any activity we do acutally do requires us to pack around all the extra weight, which is horrible on a heart used to doing nothing most of the time.
So that is what I tell people..... when I feel like grabbing that cat's tail they wag to start an argument.
Of course, this is just my opinion for what its worth.