I lived in Japan for 4 years, and I just have a couple of observations. There isn't really an "Asian" diet, like their isn't a "European" diet. It varies dramatically by country.

Just from my travel experience, China, Japan, South Korea and Vietnam cuisine all vary dramatically.

Japanese cuisine tries to focus on the original flavor of the main ingredient. That is why you won't find many dishes with heavy flavored sauces. Chinese cuisine seems to do the opposite, and Chinese cuisine is seen in Japan as very oily. Vietnamese cuisine has a strong French influence (Vietnam used to be a French colony and it shows in its cooking), and so on.

One thing I noticed though when I lived in Japan. The portions are smaller. When you go to Starbucks, the largest size is tall, which is the smallest size in the US. It is hard to eat a lot, since the portion sizes are smaller.