Give them some kind of placebo operation? Put the sufferer down and say you operated but never did? The delusion would still be there. Its mental, you cant treat my depression by telling me to smile. Friends try and point out all the things I have to be grateful for, why they would have no problems like I do if they had my life, it doesnt help. It actively makes it worse in fact. What if treating anorexia with surgery becomes addictive to that individual, and a physician says no to that treatment, what kind of reaction would the ill individual expirience?
Altering your body because something is wrong with your brain isnt the way. I have no problem with adults doing with their bodies what they will, I have no issues with adults transitioning and becoming who they feel they are. But not children. Im a very different person than 12 year old me was, than 12 year old me thought I would be. It would be horrible if I physically changed something to fit who I thought I was or wanted to be at the time, only to grow into something that is entirely different, thereby harming myself forever because of a temporary state of mind in the most difficult period of change in my life.
Which is exactly what happened in the story above.