Researchers at the University of Columbia recently conducted a study on the psychological effects caused by pro-anorexia web sites. They studied the reactions of 24 women ages 18-20 to three different web sites: one was a fashion site with average-size models, one was a home-decorating page, and the third was a typical pro-anorexia page.

"... the pro-anorexia site caused substantially negative changes in subjects' mind-sets."

The effects weren't surprising, but very telling considering the fact that each participant only viewed the web-site once. This suggests that repeated exposure to such web site could cause significant psychological damage.