It is vitally important that someone suffering from an eating disorder ensures that they are getting the best possible treatment they can. That there is a network of support around the individual (see downloadable bubble chart).
Of that network your GP must play a part in your recovery by monitoring the medical side of your condition.
An Eating Disorder is a mental health illness with physiological complications. It is vital that the psychological needs are balanced with the physical needs. If a person deteriorates to a severe or critical level, then their medical needs become the priority over their emotional needs.
It does vary in geographical areas, but if a person has a low BMI of 16.0/15.0, then that person may not be considered for therapy, as cognitively, the brain would not be able to rationalise or process that therapy as someone of a higher BMI would.