We know that anorexia, bulimia and binge are eating disorders caused by psychological problems and that have physical consequences in any person that do it for a long period of time. There are different treatments that are used to recover from it, but first you need to look for a psychological cure.
There is always a problem when dealing with people with eating disorders because they don’t want to accept that they have a problem and that it needs treatment and help for recovery. Although the teen might already have physical health issues, there wont be any major progress if she does not want to recover, so the first challenge is to make her understand and accept that she needs help.
For this to happen the support of the family is needed, there are some instances where the physical health of the teen is so dangerous that she needs to be taken to a hospital even against her will. But we want to avoid getting to that point so you will need to find a psychotherapist that can help you and guide you to deal with the problem.