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Eating disorders: Differential diagnosis

Because you are a primary care provider and not an eating disorders specialist, you have the responsibility to rule out other causes of the clinical presentation.

While people can lose weight for many reasons, the diagnosis of eating disorders requires the "nervosa" component – undue preoccupation with body weight and shape, its influence on self-perception and a morbid fear of becoming fat.

Medical differential diagnosis

The medical differential diagnosis includes:

  • hyperthyroidism
  • malignancy
  • malabsorption
  • inflammation (e.g., Crohn's disease, ulcerative colitis)

A careful history will rule out most of these possibilities, but a physical examination and laboratory investigation will also help to clarify the diagnosis and demonstrate your concern for the patient.

Other psychiatric disorders

Other psychiatric disorders can be superficially mistaken for an eating disorder. These include:

  • depression (accompanied by a true anorexia and weight loss)
  • conversion disorder (belief that something is stuck in the throat and food cannot pass)
  • schizophrenia (food avoidance based on the delusion that it is poisoned)
  • substance abuse (psychostimulants that induce weight loss)

A careful and sympathetic history will usually clarify the diagnosis. Your willingness to accept that the patient has an eating disorder will have a permissive effect on disclosure because the patient has likely already made a diagnosis via the Internet.

For many health care providers, the seemingly conscious element of control in people with eating disorders is frustrating and even infuriating. They can minimize these reactions by understanding the nature of eating disorders:

  • While issues around seeking control may catapult someone into an eating disorder, the problem ends up controlling and dominating the person.
  • While eating disorders cause numerous medical and psychiatric complications, they may also serve some adaptive function for patients (e.g., feeling more in control, being praised for weight loss). If you find out what that function is, patients are more likely to feel that you "get" them as a person beyond their weight and their symptoms.

It is also important to meet and talk with the patient's family. In addition to providing collateral history, they likely feel overwhelmed and worried and need your support.


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Frequently asked questions

Clinical guidelines

Eating disorders in over 8s: management (NICE guideline CG9, 2004)