Hiya,
Eating disorders are a lot more deep rooted than just being caused by the media - yeah, it probably does contribute towards some cases. But not all. Anorexia and Bulimia are about control, not about looking like Kate Moss.
Useful sites....
http://www.eating-disorders.org.uk/info.htm (see the 'Eating disorders and the Media' document)
http://www.something-fishy.org/cultural/themedia.php
http://www.bma.org.uk/ap.nsf/Content/Eatingdisorders
Remember that eating disorders aren't just limited to Anorexia and Bulimia, there is also Binge Eating Disorder, Eating Disorder Not Otherwise Specified, Orthorexia nervosa and Compulsive Overeating Disorder.
Hope this helps and take care,
x