One of my best friends is starting to develop severe anorexia. What should I do ?

Tell her to eat or she would just get more sick! Trust me i no......

tell someone

If you haven't, tell an adult! I'm sorry, I hope she gets better

Get an adult. The year before I met one of my closest friends, she had this and she is so glad that her friends told her parents because it's what stopped it and her depression. Just tell someone. For your friends sake