Ultimately, the answer lies in the fact that eating disorders are mental disorders, or disordered ways of viewing the world and one's own body. One suffering from an eating disorder has an illness just as does someone with diabetes. As such, an individual with anorexia should be treated in the same manner, and treatment should be given without consent, if one is not competent to refuse. Just as one would provide aide to someone in a diabetic coma without their specific instruction, so should one provide treatment, including force feeding, to someone suffering from anorexia who is unable to make a rational choice due to his or her disorder. According to the National Institute of Health, Doctors are unsure if being subjected to force feeding effects the chance of overall success of treatment. Force feeding tends to come at a point in a the disease where the individual is in danger of death, becoming an ethical issue as opposed to one of treatment. When one has starved one's self so far, one can be judged incompetent to make decisions regarding one's weight. At that point the choice becomes the responsibility of the doctor, and the doctor must do what will be best for the recovery of his or her patient P.C. Herbert and M. Weingarten discussed this in their essay "The Ethics of Forced Feeding in Anorexia Nervosa." They argue that force feeding should be done as a response to only terminal situations, and...

The patient must be in a state of emergency before resorting to a procedure that defies their expressed wishes, even if those wishes are the result of a mental disorder. Force feeding is not a long-term solution, but rather a stop-gap measure designed to get a patient through a crisis, and should be used as an emergency solution only.
At what point does a patient become competent to make his or her own choices about food? Herbert argues that providing some nutrients via force feeding can be enough to act as a "drug" for some people with anorexia, and trigger their bodies natural desire to gain weight. In these cases, force feeding is equivalent to court-required medication for individuals with other mental disorders. It allows the individual with anorexia to regain an ordered state of mind for long enough to make more competent decisions about their health. If, however, the individual does not respond to nutrients and continue to want to restrict their intake, the doctor continues to have an obligation to continue to treat the patient, even against his or her own will. It would be unethical for a doctor to allow a patient to die, in the absence of a competent advanced directive. As such, a doctor must use whatever means necessary to maintain a patients life, including the use of force feeding on individuals with anorexia.