What is the difference between Anorexia Nervosa (AN) and Bulimia Nervosa (BN)?

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From the Guidelines

Anorexia Nervosa (AN) and Bulimia Nervosa (BN) are two distinct eating disorders with different diagnostic criteria and treatment approaches. The primary difference between AN and BN lies in their characteristic behaviors: AN is marked by restriction of food intake leading to significantly low body weight, intense fear of weight gain, and body image distortion 1, whereas BN is characterized by recurrent episodes of binge eating followed by unhealthy compensatory behaviors, such as self-induced vomiting, laxatives, or excessive exercise, to prevent weight gain 1.

Key Differences

  • Restrictive eating patterns: AN is associated with restrictive eating, whereas BN involves binge eating 1.
  • Weight: AN typically results in significantly low body weight, whereas BN may not necessarily lead to low body weight 1.
  • Compensatory behaviors: BN involves regular use of unhealthy behaviors to compensate for binge eating, which is not a characteristic feature of AN 1.
  • Frequency and duration: BN behaviors must occur at least once a week for 3 months, whereas AN can be diagnosed without a specific frequency or duration of restrictive eating 1.

Treatment Approaches

  • AN: Treatment typically involves individualized nutritional rehabilitation, weight restoration, and eating disorder-focused psychotherapy, such as cognitive-behavioral therapy or family-based treatment 1.
  • BN: Treatment often involves eating disorder-focused cognitive-behavioral therapy, serotonin reuptake inhibitors (e.g., fluoxetine), and family-based treatment for adolescents and emerging adults 1.

From the Research

Difference between Anorexia Nervosa (AN) and Bulimia Nervosa (BN)

The main difference between AN and BN lies in the presence or absence of bulimic episodes, which distinguishes them exclusively 2.

  • Anorexia Nervosa (AN): characterized by restricted intake, self-induced starvation, and excessive concerns about body shape and body weight 3, 4, 5.
  • Bulimia Nervosa (BN): characterized by bingeing and purging behaviors, including self-induced vomiting and/or abuse of laxatives, diuretics, and physical hyperactivity 3, 4, 5.

Similarities and Distinctions

Both AN and BN are eating disorders with a complex etiopathology, involving psychological, developmental, biological, and socio-cultural factors 2, 4. While they share some similarities, such as an intense fear of weight gain and altered perception of body shape, they also have distinct characteristics and symptoms 2, 4.

  • Similarities: both disorders involve altered eating behaviors, excessive concerns about body shape and weight, and can have serious medical complications 3, 4.
  • Distinctions: the presence or absence of bulimic episodes, with AN characterized by restrictive eating and BN characterized by bingeing and purging behaviors 2, 3, 5.

Neurobiological and Psychological Factors

Research suggests that neurobiological vulnerabilities, such as altered brain serotonin function, contribute to the pathogenesis of AN and BN 6. Psychological factors, such as perfectionism, obsessive-compulsiveness, and dysphoric mood, are also consistently characterized in individuals with AN and BN 6.

  • Neurobiological factors: altered brain serotonin function, disturbances of 5-HT function, and dysregulation of appetite, mood, and impulse control 6.
  • Psychological factors: perfectionism, obsessive-compulsiveness, dysphoric mood, and traits that create a vulnerability for developing an eating disorder 6.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Medical Complications in Anorexia and Bulimia Nervosa.

Endocrine, metabolic & immune disorders drug targets, 2018

Research

Anorexia nervosa and bulimia nervosa: An appraisal.

Drugs of today (Barcelona, Spain : 1998), 2001

Research

Anorexia and bulimia.

American family physician, 1990

Research

Neurobiology of anorexia and bulimia nervosa.

Physiology & behavior, 2008

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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