Visiting China it became apparent that Chinese are generally thinner than Americans. I don't mean that all Chinese are thin. I saw many overweight Chinese, but I seldom saw obese Chinese.
There are two main reasons for this general observation in my opinion. First, the Chinese generally eat lower energy density foods than Americans. Rice and noodles are staples of the Chinese diet. Vegetables also generally dominate over meat in their dishes. So Chinese foods typically have fewer calories per gram than a Standard American diet. Second, the Chinese generally move more than Americans. There are many cities in China with populations greater than New York City, so a common mode of transportation in these high density populated areas is by foot.
Despite these differences, I don't view China as a healthy mecca. In fact I viewed my visit to China as unhealthy. Setting aside the poor air quality in heavily populated Chinese cities, I think the two advantages listed above are slowly evaporating. The high rate of development in China is the reason. It appears to me that the standard of living is improving in China and many Chinese are enjoying a lifestyle approaching the American standard. The American diet of fast food and meat three times per day is becoming more common in China. The Chinese love to eat meat, and the more that they can afford, the more vegetables are pushed aside. In three visits, I have yet to meat a Chinese vegetarian, pun intended. The other paradigm shift in Chinese culture is that many Chinese are working long hours in an office setting to achieve these higher standards of living. They can afford cars to commute and have little time during the day for moving their body.
I think it is only a matter of a generation or two before Chinese diet and exercise commonly resembles those of Americans, and so will they. Here are some videos from my last trip related to this topic: