A friend happens to be a model. She eats well and, apart from being very thin, is in excellent health. There are people who will stop her on the street and tell her they think she must have an eating disorder to be as thin as she is. She, like many in her line of work, is sometimes blamed for body image problems of young women.
There are a few observations - average weight has been going up for about three decades along with thin young woman imagery. While some of the models have serious eating problems others, like our friend, are healthy and happen to be thin naturally. Reasonable questions to ask might be: "does advertising impact the prevalence of eating disorders? and what is the prevalence of childhood and young obesity?"
While this doesn't get at either of those questions directly, it does look at the prevalence of eating disorders. They are often very dangerous with high mortality, but they are also much less common than obesity. Both need to be addressed, but so does the thesis that advertising somehow drives one when the other in increasing with the advertising. There may be a more complex coupling, but I've never seen that addressed satisfactorily.
An addition - please read Tetyana's comment below and check out the blog for much more information. It looks like an excellent resource.