Psychiatric diagnosis is a tricky business. I am reminded of this often when, as a research assistant at the Columbia Center for Eating Disorders, I ask people questions about their psychiatric history or current symptoms. Here I have learned that for people with eating disorder symptoms, it can be overwhelming to try and figure out what category they fit into and who to reach out to for help.
In the feeding and eating disorders section of the Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (or DSM-5), there are six different feeding and eating disorder categories, plus a group of 5 Other Specified Feeding and Eating Disorders (OSFEDs). Amongst the eating disorders, two commonly get confused – anorexia nervosa, binge-purge subtype (AN-BP) and bulimia nervosa (BN).
To better understand the differences between the two, it is helpful to turn first to the DSM-5.
The hallmark features of anorexia nervosa (AN) are a reduced consumption of calories that results in an abnormally low weight for adults or a failure for kids and teens to grow as they should, a fear of weight gain or becoming fat (or an inability to eat in a way that supports a healthy weight), and a distortion of or overemphasis on body weight and shape. People with this disorder commonly have difficulty recognizing the seriousness of not eating enough for their body’s needs.
While approximately 50% of adults with AN have the restricting-only variant of the disorder, the other half meet criteria for the binge-purge subtype of the disorder, characterized by recurrent binge eating and/or purging. Purging refers to inappropriate behaviors that aim to compensate for food consumed and can involve self-induced vomiting or misuse of medicines like laxatives, diuretics, or enemas.
Like, those with AN-BP, people with BN experience regular binge eating and purging (at least once weekly over a 3-month timeframe). However, those with BN engage in both binge eating episodes and purging behavior, not one or the other. And, importantly, people with BN have weights within or above a normal range. Like those with AN, people with BN tend to eat restrictively (outside of binge episodes) and are very concerned with and focused on their body weight and shape. These aspects of appearance are a major factor in how people with these disorders evaluate themselves, and severe dissatisfaction is common.
Part of the confusion between AN-BP and BN is historical. Before the publication of the DSM-IV in 1994, people could be diagnosed as having both AN and BN at the same time. It wasn’t until 1994 that the American Psychiatric Association noted the differences between the two disorders, and separated AN into its two subtypes. While individuals now are diagnosed as either having AN-BP or BN instead of both at once, it is important to know that it is possible to crossover from one diagnostic category to the other, based on weight changes.
In research looking at the diagnostic crossover in an adult, female sample over 7 years, 54% of individuals with an intake diagnosis of AN-BP crossed over to BN. And approximately half of this group crossed over in the course of progressing to partial or full eating disorders recovery (a good reminder that recovery is possible!), whereas the other half who experienced crossover to bulimia nervosa were likely to cross back over into AN. A much smaller proportion (14%) of people with an intake diagnosis of BN when on to meet criteria for AN, but all who crossed over did so to the binge-purge subtype.
While the differences between the two eating disorders may not seem to be that big of a deal, proper classification is useful both to patients who are seeking treatment and for the clinicians providing it. Treatment for both disorders will of course target the normalization of eating, breaking of binge eating and/or purging behaviors, and improving body image, but the mechanisms by which this is accomplished will vary slightly. For example, those with AN-BP will need to restore weight to maximize health, and will need to think carefully with their clinician about what level of care will help them accomplish this goal (and/or if a family-based approach might help). Those with BN may want to avail themselves of psychotherapies shown to work in the treatment of their disorder – cognitive behavioral therapy as a first-line treatment and interpersonal therapy as a second-line treatment – and/or evidence-based use of psychotropic medication.
If you or someone you know is experiencing symptoms of a feeding or eating disorder and is looking for treatment, read up on seeking mental health care (as well as common myths about treatment) and consider the following referral resources:
- Give us a call at 646-77-8066 or email us at edru@nyspi.columbia.edu
- National Eating Disorders Association– Contact this national US helpline for a list of specialized, eating disorder treatment resources.
- American Psychiatric Association– Find a psychiatrist to provide a comprehensive psychiatric evaluation, including medication recommendations.
- Association for Behavioral and Cognitive Therapies– Search for a cognitive behavioral therapist by location, specialty, and insurance.
- Psychology Today– Search by a variety of factors, like location, specialty, and insurance for an outpatient psychotherapist.
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