Japanese teenagers diets

Hi,
i've noticed that japanese in general are thinner than westerners.however,some teenagers i noticed were much thinner than the average,kinda scarily so.i'm curious to know how common it is for teenagers to have eating disorders or any dieting extremes they may go to?obviously similar things happen everywhere,but i'm just interested.thanks to any info.

Eating disorders (kyoshokusho/kashokusho) and dieting extremes (kageki na daietto) are serious issues that every person living in Japan are aware of. I also think that almost every teenage girl, no matter the generation or country, has experienced extreme dieting to the point that they got sick in one way or another, and today we are not surprised when a girl appears on TV saying she was reciebing medical treatment for suffering eating disorder.

However, although I'm not sure where you see those skinny Japanese teenagers, generally speaking the Japanese (including teenagers and non-teenagers) are quite skinnier than say the average American. It's partially genetic, but what you eat is quite different. Although Japanese teenagers sneak to eat their lunch during the morning hours, go to the cafeteria at noon, go out for burgers after school, and eat mom's supper in the evening, you don't eat ice cream direct from the carton here and restaurant portions are much smaller. They also commute by subway and buses, so they can't help but to do a lot of walking. It is a known fact that when a Japanese teenager goes to the U.S. for a year as an exchange student, (s)he comes home a bit more chubbier. In any case, actually seeing the thighs of high school girls wearing those mini school uniforms in the streets of Japan, I can't imagine they have serious diet problems :)