Adolescents in China are getting taller, but weaker

Beijing's Olympic Forest Park is busiest after sunset, when adults go for an after-dinner stroll or a run.

Children are there too, but seldom do teenagers show up. Teens are generally at home, working on math or English grammar. But while they are getting higher scores, they are also getting fat, weak and lazy.

Seven national surveys on the health of China's adolescents from 1985 to 2014 show a decline in fitness, despite better nutrition.