A psychiatrist may diagnose an individual with eating disorder by assessing her/him on a symptom criteria laid down by either ICD (International Classification of Diseases) or DSM (Diagnostic Statistical Manual of Mental Disoders). If the patient is meeting the symptoms criteria laid down by these two manuals for either anorexia, bulimia or binge eating, then s/he may be asked to take certain laboratory tests to ensure a proper diagnosis. This is a non-invasive procedure that may require multiple visits. But, it helps to ascertain the eating disorder an individual may be suffering from by distinguishing between the symptoms of various disorders.

Developed by Probst and his colleagues in 1995, Body Attitudes Test or BAT is used to assess eating disorders in females. It is a non-invasive, self report measure that allows women to express their subjective body experiences and their perceived attitudes about their body type. A women with an eating disorder may show negative attitude towards her body size, may express a lack of familiarity with her body, and display a general body dissatisfaction. The test is mainly used for diagnosing bulimia and anorexia, and requires a single visit for performing the test.

This is an interview conducted by a clinician to assess eating disorder. The interview technique was devised by Fairburn and associates in 1987. Herein, a clinician may assess an individual on four sub scales: restraint, eating concern, shape concern and weight concern. The patient is observed for a period of 28 days and the question of concern is the frequency in which a patient displays behavior indicative of an eating disorder.

This is a relatively simple, non invasive procedure wherein an individual’s current weight and height are recorded. If a person’s BMI is from 19 to 25, then s/he is considered healthy, but if the BMI is less than 17.5, it may indicate anorexia while a BMI more then 30 may indicate binge eating disorder. This analysis helps in understanding and differentiating whether an individual has bulimia nervosa or binge eating disorder or not.

An individual who may appear to have either anorexia or bulimia may have to undergo an invasive procedure of a complete blood count test. This test calculates the individual’s white and red blood cells along with platelets. This allows the professional to make a proper diagnosis and also helps him to know whether the patient is suffering from associated disorders like anemia, thrombocytosis and leukocytosis or not. 

To understand the possible causes of an eating disorder, an individual may have to undergo neuroimaging procedures such as MRI, PET Scan and SPECT imaging. These tests diagnose any possible tumors, lesions or conditions that might have attributed to the eating disorders. Along with this, a non-invasive thorough physical examination may be conducted if the patient’s eating disorder seems to be worsening. Skin temperature may be checked for hypothermia that is associated with anorexia.

The therapist may ask for a psychological evaluation wherein the individual is kept under observation. This requires multiple visits to the clinician. The clinician herein tries to understand the possible triggering factors of eating disorders like stress, low self esteem, troubled relationships or depression. This allows them to make a proper assessment and a differential diagnosis if necessary.