How Do You Treat Anorexia?

You ought to normalize the patient's weight. It may be necessary to insist on hospital care where drip-feeding can be used. If the patient refuses to accept nutrition then sedatives are required in order to make it possible.

A person with anorexia need to talk with a therapist.  This person has a mental disorder that needs a doctor just like any other sickness. In the meantime, help them understand that there are chemicals in their brain making them feel the way they do about themselves.  Their thoughts are not valid, but it's also not something they can control (the way they feel that is).  If you simply force them to gain weight without fixing these perceptions of themself they will be depressed and/or become anorexic again.  I wish you the best of luck.