Understanding Atypical Anorexia Nervosa

A history of higher weight is common in individuals seeking treatment for eating disorders. Among these individuals, a large group is diagnosed with atypical anorexia nervosa (AN). The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) introduced this new diagnostic category in 2013 for people that met all the criteria for AN, except that despite significant weight loss, their weight is within or above the normal range.

Several studies have been published on atypical AN in the last 10 years. Now we have a better knowledge of its clinical characteristics, which I will summarize in the following sections (for more information, you can read a recent review published in the International Journal of Eating Disorders), together with some new strategies used by the enhanced cognitive behavior therapy (CBT-E) to address this eating disorder.

Epidemiology, gender, and race/ethnicity

A recent review concluded that although atypical AN seems more frequent than AN in communities, fewer individuals with this disorder are referred and admitted to eating disorder clinical services. Factors contributing to this discrepancy include the bias against identifying restrictive eating problems in not underweight individuals and the difficulties in assessing what constitutes “significant weight loss” (see below).

Available studies also indicate that a more significant proportion of males and non-white individuals suffer from atypical AN than those with AN.

Significant weight loss and body weight

Surprisingly, most studies on atypical AN did not report a definition of weight loss. However, at least 10 percent or greater weight loss was the most common threshold used, although a study examining the relationship between three degrees of weight loss (5 percent, 10 percent, and 15 percent) concluded that even a 5 percent weight loss is associative with increased psychopathology and distress compared to controls. In addition, no study provided detailed information regarding the time course of the weight loss. This information is of great clinical utility as the rapidity of weight loss is associated with an increased risk of medical complications. In addition, individuals with atypical AN are also more likely to have a history of higher weight and maximum body mass index (BMI) than those with AN.

Psychological symptoms

Available data indicate that the severity of eating disorder symptoms (i.e., preoccupation with eating, shape, weight, dietary restraint) is as high or higher as among individuals with AN. In contrast, levels of anxiety and depression are similar.

However, individuals with atypical anorexia, as they have experienced higher weights as children (and weight-based teasing) and present with higher weights than those with AN, are more likely to experience weight stigma (i.e., negative attitudes and manifested beliefs involving stereotypes, rejection, and prejudice toward people perceived as having higher body weight) in healthcare settings and by healthcare providers (e.g., pediatricians, primary care providers, eating disorder specialists).

Some studies have shown that weight stigma, when internalized (i.e., people’s self-directed stigmatizing attitudes based on social stereotypes about their perceived weight status), can predict lower core self-evaluation, which in turn predicts greater depression and anxiety, maladaptive eating behaviors, lower global health, and greater healthcare utilization. In addition, weight stigma in healthcare seems to be a risk and maintenance factor of eating disorder behaviors. It negatively impacts the treatment of eating disorders, delaying care and creating inadequate treatment environments and approaches and mistrust of healthcare professionals.

Physical complications

Individuals with atypical AN experience many physical complications associated with AN, but some complications appear less frequent.

For example, the frequency of menstrual disturbance in atypical AN individuals is significantly lower than reported by those with AN. However, it is greater than those of controls. Similarly, the frequency of abnormal cardiac measures (e.g., hypotension and bradycardia) is similar or somewhat lower in adolescents with atypical AN compared to those with AN. Individuals with atypical AN also have a higher bone mineral density than those with AN, similar to controls. Finally, no significant difference between individuals with atypical AN and controls was found in the gray and white matter volume and microstructure estimate.

Course and treatment outcome

The only available study on the course of atypical AN assessed 14 individuals with this eating disorder and found that the average episode duration was 11.2 months, with a remission rate of 71 percent within one year and a recurrence of the eating disorder in 21 percent of cases. No individuals with atypical AN developed AN.

A case series of 42 adolescents with atypical AN treated with family-based treatment (FBT) found that 37.5 percent of patients achieved full remission and another 25 percent a partial remission with no significant change in percent of median BMI for age and gender. On the contrary, in another study of 41 young patients treated with FBT, only 49 percent completed the treatment, and the patients achieved a mean weight gain of 10 kg during the treatment.

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The challenges of determining a weight treatment goal

The amount of total weight loss better explains the psychosocial symptoms and medical complications among individuals with atypical AN than their actual body weight. This observation indicates that in most cases, individuals with atypical AN, although they are not underweight, need to regain some weight to achieve a healthy psychological and physical condition.

However, it is unclear how much weight is necessary to recover from atypical AN, and clinicians have different opinions. For example, in one study, clinicians treating young with atypical AN recommended 56 percent of patients gain weight and 44 percent stabilize weight, despite all the patients having significant weight suppression. Clinicians also reported that identifying the goal weight in these patients was the most clinical challenge when delivering FBT.

As sustained by some authors, this disagreement in treatment recommendation might reflect the internalization of weight stigma among clinicians that influence their decision to address or not weight regain in individuals with eating disorders who are not underweight.

The strategies used by CBT-E

In CBT-E, an evidence-based treatment for all eating disorders I practice and teach, the patients are first collaboratively helped to evaluate the need to change and regain weight (if indicated). Indeed, the goal of CBT-E, contrary to other treatments for eating disorders, is that the patients decide to regain weight rather than having this decision forced upon them. If patients at the end of step one of the treatment, which lasts about four weeks, disagree on change, the treatment is stopped, but this is not a frequent occurrence.

As body weight is strongly influenced by genetics, and several potent biological mechanisms act to restore weight lost, once the patients have decided to attempt weight regain, the weight goal is tailored to the characteristic of the individuals. As a general strategy, the goal of CBT-E is for the patients to achieve a natural body weight that satisfies all the following conditions: (1) it can be maintained without adopting extreme weight-control behaviors, (2) it does not cause psychosocial and medical complications, and (3) it is compatible with physical health and normal development.

In parallel with weight regain, the treatment also addresses with a flexible, personalized, and health-centric approach (rather than a weight-centric approach) the other features of the patients eating disorder psychopathology (e.g., body image, dietary restraint and restriction, events and moods influencing eating). In addition, in patients with atypical AN, much work is dedicated to helping them accept their natural body weight that is biologically higher than the sociocultural ideal, thin, and muscular body and, if indicated, the internalized weight stigma.