Here is an article I found on the Star Magazine site about Mary-Kate and her thiness. It does not say that she has an eating disorder for sure, but there are several suspects.

http://www.starmagazine.com/news/61346

Originally posted by Jen1989
I noticed that in some of the pictures of the Olsen Twins that they don't seem to smile much. Are they really that unhappy? Or maybe they get tired of having their picture taken? I think they try to go for a more serious look. When they were younger, I remember one would smile with their teeth and the other would give more of a smirk or half smile, but with no teeth showing. I am pretty sure Ashley was the one that smiled with teeth.