Diagnosing bulimia nervosa is complicated by the secrecy and denial used by bulimics to mask binging and purging. Unlike anorexia nervosa, bulimia is not accompanied by a significant weight loss. The lack of weight loss makes it less likely that family members will identify bulimia nervosa.
Bulimics rarely seek medical help for binging and purging behaviors. The disease is most likely to come to a doctor’s attention when the bulimic seeks help for health complications arising from binging or purging, or for an unrelated health problem.
Unlike anorexics, most people with bulimia nervosa are aware they have unhealthy eating habits, and may even be aware they have an unhealthy obsession with weight loss. Bulimics are less likely to resist diagnosis and treatment than anorexics, and more likely to provide accurate information about their binging and purging habits and attempts at weight loss.
The DSM-IV and Bulimia Diagnosis
The American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV) provides the criteria by which a diagnosis of bulimia nervosa is made. Duration and frequency of the binging and purging cycle is an important factor for diagnosis, as is the patient’s attitude towards weight loss and body image. In all, five criteria must be met before a diagnosis of bulimia is considered:
- Binge Eating: The DSM-IV defines binging associated with bulimia nervosa as eating in a “discrete time period” an amount of food significantly greater than expected of normal eating habits.
- Purging: Purging is defined as “recurrent inappropriate compensating behavior” to prevent weight gain after episodes of binging. Purging behavior associated with bulimia nervosa includes self-induced vomiting, misuse of laxatives, diuretic use, enemas, fasting, and excessive exercise.
- Frequency and Duration: For a diagnosis of bulimia nervosa, episodes of binging and purging must occur at least twice a week for three consecutive months.
- Body Image and Weight Loss Attitudes: Bulimics, like anorexics, have a great fear of weight gain, and self-evaluate almost completely in terms of body image and weight loss. A bulimic has an unrealistic image of his or her ideal weight; usually well below the healthy minimum of the individual’s age, gender, and height.
- Absence of Anorexia: A cycle of binging and purging is not considered bulimia if it occurs during an episode of anorexia nervosa. Instead, the patient is said to have binge and purge type anorexia.
Types of Bulimia
If all of the DSM-IV’s criteria for bulimia nervosa are met, the diagnosis must determine what subtype of bulimia affects the patient. The two broad categories for bulimia are:
- Purging Type Bulimia Nervosa: Binging is followed by purging behavior (vomiting, laxative use, and other techniques to quickly rid the body of consumed calories).
- Non-Purging Type Bulimia Nervosa: Rather than purging after episodes of binging, the bulimia patient fasts or exercises excessively to prevent weight gain or achieve weight loss.
Differential Diagnosis: Is It Really Bulimia?
Before bulimia nervosa is diagnosed, any mental or physical conditions that mimic the eating disorder must be ruled out. Of these conditions, distinguishing between anorexia and bulimia is of vital importance. Bulimia patients often have a history of anorexia, so symptoms may indicate an anorexia relapse. Doctors must differentiate between bulimia nervosa and binge and purge type anorexia.
One way to distinguish the two eating disorders is by weight loss. While both bulimics and anorexics obsess on weight loss and weight gain, bulimics are generally of average weight or slightly overweight. Bulimics tend to have frequent weight fluctuations, with weight loss followed by subsequent weight gain. Anorexia is characterized by progressive weight loss.
In addition to anorexia, a number of disorders may mimic bulimia, including:
- borderline personality disorder
- brain tumors
- epileptic seizures
- Klein-Levin syndrome (a rare condition more common in men that causes excessive eating)
- Kluver-Bucy syndrome (a rare condition causing excessive eating, hypersexuality and compulsive licking/biting)
- obsessive compulsive disorder
- upper gastrointestinal disorders.
American Psychiatric Association. Diagnostic criteria for 307.51: Bulimia nervosa. Diagnostic and Statistical Manual of Mental Disorders, 4th Edition. American Psychiatric Association, Washington, DC, 1994.