If you are a teenage girl, the values of the world you walk around in, and certainly the values of your friends, influence your risk for developing an eating disorder. I think this is just the tip of the iceberg, so to speak. From where I sit, this is not just true for teenage girls-they were simply the subjects for this study.
"It appeared that changing attitudes within a group that had been exposed to television were a more powerful factor than actually watching the programs themselves. In fact, higher peer media exposure were linked to a 60 percent increase in a girl's odds of having a high level of eating disorder symptoms, independently of her own viewing."
http://www.physorg.com/news/2011-01-secondhand-television-exposure-linked-disorders.html