Pretty easy for me to see why Japanese women weigh less than Americans:
- Asian women are typically shorter and have a smaller natural body frame. So right away a Japanese female will be lighter
- But even if you compare women of same height, nobody needs to be a scientists to see the differences. Lots of fat people in the US
1. Eat too much
2. Too much junky food
3. Too many buffets, huge portions, butter, greasy food, booze, Starbucks frappacino runs, soft drinks etc.....
That's all you need to know.
I don't see any kind of stereotype that Japanese people are always working out and hitting the gym like they are exercise nuts. In fact, I wouldn't be surprised if the avg American hits the gym and plays more sports more often. But whatever weight they lose working out gets overcompensated by the calorie counts of food they eat.
Interestingly, Asian culture has lots of carbs (rice and noodles). And this stuff is high calorie. So it goes to show there's other shit Americans eat (and other Western people eat) that goes well beyond whatever calories rice and noodles are worth.