I'm not sure why people are claiming these kinds of ads can cause eating disorders. They can cause feelings of inadequacy, sure, but feeling inadequate is almost never the sole cause of any mental illness. This is a paragraph from a fairly old paper, but it is still very relevant to this thread:
Source:
http://www.annualreviews.org/doi/pdf/10.1146/annurev.psych.53.100901.135103
The people who are already at high risk of developing eating disorders (due to genetic, biological, personality, etc. individual risk factors) would be pushed over the edge if not by this ad, then by other sources of body dissatisfaction that are either unavoidable (e.g. they come across real skinny people in real life!) or that they might actually willingly seek out (e.g. pictures of models with incredible bodies on Instagram).
To say that this ad will contribute to incidence of anorexia or other eating disorders is pure hyperbole.