I had a look at BEAT Eating disorders online support services. They have rigorous ground rules for users about confidentiality, removal of all identifying data and strict moderation, including unambiguous safeguarding information reminding users that they will refer to the police / other agencies if they believe a child is at risk. They ban all sorts of discussions about dieting and food, suicide and self harm. There's 4 pages of ground rules.
In other words they put in place boundaries to keep children safe online. Unlike the current dangerous group that we're discussing
I also looked at what BEAT say about the unregulated pro ana, pro mia sites and BEAT openly steer children away saying:
"The terms “pro-anorexia”, or “pro-ana”, and “pro-bulimia”, or “pro-mia”, refer to content, usually online, that promotes the harmful behaviour and mindset that forms part of some eating disorders.The sites and social media where such content is found often say or imply that this behaviour is a lifestyle choice, rather than symptoms of an illness" (now where have we seen this before?)
www.beateatingdisorders.org.uk/
The difference is stark when looking at BEAT's professional boundaried online resource devoted to supporting unwell children - there's a grim contrast when looking at the glittery shambles of an adult ideologically driven site devoted to gaslighting equally vulnerable children.