Do you know why people in Japan are so much skinnier on average than people in the USA?
user
Yeah, this is a commonly observed cultural difference.  It’s interesting that you were curious about this, since a lot of people wouldn’t think to make this connection.  Japan has historically had a lower income standard, and therefore lower-quality foods, so many more people suffer from malnutrition.  Also, there is less of a cultural emphasis on eating lots of rich foods.  These factors probably play an important role.
assistant
Do you know why people in Japan are so much skinnier on average than people in the USA?
user
I think there are some important reasons, but I’m not completely sure why.  How can I help you learn more?
assistant
Do you know why people in Japan are so much skinnier on average than people in the USA?