Given the similarities between bulimia nervosa and anorexia nervosa, binge-eating/purging type, there's room for confusion when making a diagnosis, whether on the ASWB exam or in real life. Let's take a look at what the DSM says about each.
What is anorexia nervosa?
Criteria for anorexia nervosa are as follows:
A. Restriction of energy intake leading to significantly low body weight.
B. Intense fear of gaining weight despite significantly low weight.
C. Disturbance in the way one's body weight or shape is experienced, undue influence of body weight shape on self-evaluation, or persistent lack of recognition of the seriousness of current low body weight.
What are the types of anorexia nervosa?
There are two subtypes in anorexia nervosa:
Restricting type. Weight loss accomplished primarily through dieting, fasting, and/or excessive exercise (not recurrent binging or purging).
Binge-eating/purging type. Recurrent episodes of binge eating or purging (self-induced vomiting or the misuse of laxatives, diuretics, or enemas).
What is bulimia nervosa?
Criteria for bulimia nervosa are as follows:
A. Recurrent episodes of binge eating (overeating in a discrete period of time with a sensed lack of control regarding the eating).
B. Recurrent inappropriate compensatory behaviors to prevent weight gain (e.g., self-induced vomiting, misuse of laxatives, diuretics, or other medications; fasting; excessive exercise).
C. Lasts once a week for three months.
D. Self-evaluation is unduly influenced by body shape and weight.
E. Does not occur exclusively during episodes of anorexia nervosa.
What's the difference between anorexia nervosa, binge/purging-type and bulimia nervosa?
Both anorexia nervosa and bulimia nervosa involve negative self-evaluation of body shape and weight. Both involve behaviors to avoid weight gain such as self-induced vomiting. However, in anorexia nervosa, the disorder leads to significantly low body weight, where bulimia nervosa does not.
The difference is the ways severity is coded for anorexia and bulimia helps highlight the essential difference between the two diagnoses.
For anorexia nervosa, severity is based on body mass index (BMI). For example, "mild" indicates a BMI less than or equal to 17 kilograms per square meter. "Extreme" indicates a BMI of less than fifteen kilograms per square meter.
For bulimia nervosa, severity is based on the frequency of behaviors. For 1-3 episodes per week, a specifier of "mild" is applied. "Extreme" is used for 14 or more episodes per week.
The difference is not the behavior itself, it's the result.
Free ASWB Exam Practice
The ASWB exam often tests to assess knowledge of differentials between commonly occurring DSM disorders like anorexia and bulimia. A sample question:
A 17-year-old client who appears noticeably underweight reports frequently forcing herself to vomit after meals in order to "stay skinny for cheerleading." The MOST likely DSM diagnosis for this client is a type of:
A. Bulimia nervosa
B. Body dysmorphic disorder
C. Rumination disorder
D. Anorexia nervosa
Unless you're caught by the distractors, body dysmorphic disorder (which is not diagnosed when an eating disorder is present) and rumination disorder (not described here), knowing the difference between anorexia and bulimia quickly gets you to the correct answer. The client is "noticeably underweight." You have your essential information. The phrase "a type of" at the end of the question stem is an additional clue. The client is most likely suffering from anorexia nervosa, binge/purging-type. The answer is D.
[Post by Will Baum, LCSW]
February 12, 2019