Atypical anorexia mirrors anorexia with restrictive eating behaviors and psychological distress, yet even after weight loss from unhealthy behaviors, people with atypical anorexia maintain a BMI in or above the “normal” range.

Eating disorders can take various forms. It might be surprising to learn that anorexia nervosa, which is typically linked to extremely low body weight from unhealthy eating behaviors, can also affect people with moderate or higher body weights.

This version, known as atypical anorexia nervosa (AAN), has the same symptoms as anorexia nervosa (AN). But in AAN, the person experiencing unhealthy weight loss still has a body mass index (BMI) in the “normal” range or higher.

AAN is a relatively recent diagnosis identified in the Diagnostic and Statistical Manual of Mental Disorders, 5th edition, text revision, under “Other Specified Feeding or Eating Disorders (OSFED).”

AAN has the same criteria as AN except for weight. In AAN, a person’s weight remains in the “normal” range or higher despite significant weight loss. As a result, healthcare professionals commonly miss or underestimate the condition, which can lead to delays in treatment.

People with AAN experience similar — and sometimes even more severe — medical and psychological complications compared to those with typical AN, including hypophosphatemia (low serum phosphorus levels).

People with AAN may develop these medical complications due to rapid weight loss resulting from behaviors such as restrictive eating, self-induced vomiting, or other disordered eating patterns.

Is atypical anorexia nervosa common?

In recent years, there has been a significant increase in the number of people in larger bodies who seek care in specialized eating disorder programs. A 2022 research review suggests that people in larger bodies make up 25–45% of those in inpatient medical stabilization units.

A 2021 review reported that AAN may have a higher prevalence than low weight anorexia. However, AAN is observed less frequently in clinical settings.

The authors reviewed 58 studies of consecutive referrals and admissions to eating disorder centers and found that in roughly 71% of those studies, people with AAN accounted for at least 10% of the people who sought treatment.

In addition, the review authors found that some treatment centers reported a notable surge in the number of AAN cases within particular time frames. For instance, one 2014 study showed more than a fivefold increase in AAN cases among adolescents in a 6-year period.

Common symptoms of AAN include:

  • Significant weight loss: potentially dangerous weight loss due to restrictive eating, fasting, excessive exercise, self-induced vomiting, laxative use, and other behaviors, despite remaining within or above a “normal” weight range
  • Fear of weight gain: a preoccupation with body weight and shape and a fear of gaining weight or becoming fat
  • Restrictive eating patterns: severe dieting, avoidance of certain foods, or restriction of overall food intake
  • Body image disturbance: a distorted perception of your body shape or weight
  • Physical health issues: symptoms such as fatigue, dizziness, fainting, hair loss, gastrointestinal problems, irregular menstruation, and cold intolerance
  • Psychological and emotional changes: increased anxiety, mood swings, irritability, social withdrawal, and preoccupation with food, dieting, and body image

Like other eating disorders, AAN is influenced by a combination of factors:

  • Genetics: Having a family history of eating disorders may increase your risk of developing one. Some older research suggests that female family members of people with anorexia are 11 times more likely to develop AN than relatives of people without AN.
  • Psychological and emotional factors: Certain personality traits, such as perfectionism, impulsivity, and high levels of neuroticism, tend to be linked with eating disorders. These are often paired with reduced self-directedness, assertiveness, and cooperativeness.
  • Sociocultural influences: Societal pressures, cultural emphasis on thinness, and media portrayal of the “ideal” body image can significantly affect body dissatisfaction and trigger disordered eating behaviors (DEB). One 2018 study evaluating the effects of peer pressure on eating disorders in Jordan found that 31.6% of adolescents had DEB.
  • Traumatic events: Trauma can sometimes trigger the onset of an eating disorder in people who are susceptible. A 2022 study found that sexual interpersonal trauma was significantly linked to anorexia and binge eating disorder.
  • Sports and athletics: Sports can potentially increase the risk of an eating disorder. Restrictive dieting and excessive exercise can result from wanting to obtain the ideal athletic body or reach peak athletic performance. Another possible symptom is intensely exercising even when injured in order to stay in shape.

AAN can lead to several potential health complications that are similar to those seen in typical AN, including:

  • Nutritional deficiencies: As a result of restricted food intake, AAN may lead to deficiencies in essential nutrients, which can cause weakness, fatigue, and other health issues.
  • Electrolyte imbalances: Severe restrictions in food intake can disrupt electrolyte balance, leading to complications such as irregular heartbeat, weakness, and (in extreme cases) heart issues.
  • Gastrointestinal problems: Prolonged food restriction can lead to digestive issues such as constipation, bloating, and stomach pain.
  • Hormonal disturbances: AAN can disrupt hormone levels and can particularly affect menstrual cycles in females, leading to irregular or absent periods.
  • Bone density loss: Inadequate nutrition and hormonal imbalances can contribute to a decrease in bone density, increasing the risk of fractures and osteoporosis.
  • Cardiovascular complications: Severe malnutrition can affect heart health, causing issues such as low blood pressure and fainting.
  • Mental health complications: AAN can worsen or lead to mental health issues such as anxiety, depression, and social isolation due to preoccupation with food and body image.

Treatment for AAN typically involves a multidisciplinary approach tailored to your specific needs. This may include:

  • Medical supervision: Regular medical checkups and monitoring of vital signs, electrolyte levels, and overall health status are essential, especially if there are significant physical health complications.
  • Nutritional counseling: A registered dietitian can help you establish healthy eating patterns, balance your nutrition, and overcome food-related fears or restrictions.
  • Therapy: Some forms of therapy, such as cognitive behavioral therapy, dialectical behavior therapy, and group therapy, are effective in addressing underlying psychological factors, body image concerns, and disordered eating behaviors.
  • Medication: In some cases, medications such as antidepressants or anti-anxiety drugs might be prescribed to manage co-occurring mental health conditions. However, evidence for the use of medication in treating anorexia is lacking.
  • Family involvement: Family therapy or support can be beneficial, especially in cases involving adolescents or when family dynamics contribute to the eating disorder.
  • Education and support groups: Participating in support groups or educational programs can help you connect with others who are facing similar challenges and learn coping strategies.

Atypical anorexia nervosa challenges the stereotypical image of anorexia, affecting people who do not have a very low body weight or BMI. Despite this difference, it can be equally severe and sometimes even more severe.

If you suspect that you have atypical anorexia, don’t hesitate to seek help from a healthcare professional or eating disorder specialist. They can provide a diagnosis, guide your treatment, and offer support and resources.