I think we should agree that women and girls physically harming themselves is "harmful".

> Frances Haugen: And what's super tragic is Facebook's own research says, as these young women begin to consume this-- this eating disorder content, they get more and more depressed. And it actually makes them use the app more. And so, they end up in this feedback cycle where they hate their bodies more and more. Facebook's own research says it is not just the Instagram is dangerous for teenagers, that it harms teenagers, it's that it is distinctly worse than other forms of social media.

I just started listening to this https://www.audible.com.au/pd/More-Than-a-Body-Audiobook/035... which shows directly through research how this kind of depression leads to physical self harm.

Now I'm questioning why I even want to have an Instagram account.

The "who defines" question isn't really much of a gotcha for laws. Either the legislature specifies when the pass the law, or courts get to decide when a case comes before them. Sometimes a jury is also involved.