Research has shown that young women exposed to pro-ana websites felt more negative, had lower self-esteem, perceived themselves as heavier and were more likely to compare their bodies with other women...
Dr Ty Glover, consultant psychiatrist on the Eating Disorders Unit at Cheadle Royal Hospital, said it had proven difficult to shut down pro-ana websites, but the situation was slightly different for sites such as Facebook.
"Social networking sites can censor their material and we expect them to act responsibly," he said.
"We are horrified at the content of these sites and the tips they give on how to be thin.
"People with eating disorders are extremely vulnerable and often have very low self esteem, so pro-ana and pro-mia sites can be very damaging as they are sending out the wrong advice."
So let's be completely clear about this: Facebook and MySpace are currently hosting groups that tell sick girls, on the brink of starvation, to ignore health care professionals and continue to fast, and even provide advice on what illegal drugs to use to get thinner. And they apparently think that's OK, because it's been brought to their attention several times and they've done virtually nothing about it.
If any of the folks running Facebook or MySpace are the parents of young girls, I really don't know how they sleep at night knowing this.
BBC asked MySpace and Facebook to respond to the article. (That's what good journalists do.)
MySpace said they're resisting censorship but at least they're doing something:
"It's often very tricky to distinguish between support groups for users who are suffering from eating disorders and groups that might be termed as "pro" anorexia or bulimia.
"Rather than censor these groups, we are working to create partnerships with organisations like B-eat.
"We have also placed ads on pro-anorexia profiles for up to a year from the National Eating Disorder Association to target these groups with positive messaging about how and where they can get help."
Facebook, however, gave the same stock answer to BBC that they gave me last summer when I asked them the same question for my October 5 Business Lexington column:
"Many Facebook groups relate to controversial topics; this alone is not a reason to disable a group.
As for censoring "controversial" content, we all remember that Facebook had no problem banning a member for posting a picture of herself breastfeeding two children.
Heck, Facebook even banned a picture of a Swedish cartoon character because - Bless my stars! - he had nipples.
You read that right- Facebook banned a Swedish kids' male cartoon character with nipples, but still refuses to ban groups that tell anorexic girls how to lose even more weight by starving themselves and taking illegal narcotics.
It's sad - thanks to all the ranting I've done about this issue, I actually get about as much search engine traffic from people going to google looking for "pro-ana" or "anorexia pictures" as I do from people looking for tips on blogger relations and social media. But I'm fine with that if people read what I'm writing and are motivated to do something.
I don't envy Facebook's job here. Nobody will ever be a perfect free-speech traffic cop. But this is such an obvious error in judgment.
I think it's about time we asked our politicians and candidates what they think about this.