What are the DSM-V (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition) criteria for anorexia nervosa?

DSM-5 Diagnostic Criteria for Anorexia Nervosa

The DSM-5 requires three core criteria for diagnosing anorexia nervosa: (1) persistent restriction of energy intake leading to significantly low body weight in context of age, sex, developmental trajectory, and physical health; (2) either intense fear of gaining weight or becoming fat, or persistent behavior that interferes with weight gain despite significantly low weight; and (3) disturbance in the way one's body weight or shape is experienced, undue influence of body shape and weight on self-evaluation, or persistent lack of recognition of the seriousness of the current low body weight. 1

The Three Essential Diagnostic Criteria

Criterion A: Significantly Low Body Weight

• Persistent restriction of food intake leading to body weight that is significantly lower than minimally expected for the patient's age, sex, developmental trajectory, and physical health 1, 2
• This represents a shift from DSM-IV, which specified a rigid BMI cutoff; DSM-5 allows for more clinical judgment in determining what constitutes "significantly low" 1

Criterion B: Fear of Weight Gain or Interfering Behaviors

• Either an intense fear of gaining weight or of becoming fat, OR persistent behavior that interferes with weight gain, even though the patient is at significantly low weight 1
• This criterion was broadened in DSM-5 to include patients who may not explicitly verbalize fear but whose behaviors clearly demonstrate it 1

Criterion C: Body Image Disturbance

• Disturbance in the way one's body weight or shape is experienced 1, 2
• Undue influence of body shape and weight on self-evaluation 1
• Persistent lack of recognition of the seriousness of the current low body weight 1

Subtypes of Anorexia Nervosa

The DSM-5 maintains two subtypes based on the presence or absence of binge-eating and purging behaviors:

Restricting Type

• Weight loss achieved primarily through dietary restriction, fasting, and/or excessive exercise 1
• No regular engagement in binge eating or purging behaviors 1

Binge-Eating/Purging Type

• Regular engagement in binge eating and/or purging behaviors (self-induced vomiting, misuse of laxatives, diuretics, or other medications) 1, 2
• Critical distinction from bulimia nervosa: patients maintain significantly low body weight, whereas those with bulimia nervosa do not 3, 4

Key Changes from DSM-IV to DSM-5

Amenorrhea Criterion Removed

• DSM-IV required absence of at least three consecutive menstrual cycles; this criterion was eliminated in DSM-5 1
• This change increased the diagnostic prevalence by approximately 60% in research populations 5
• The removal allows diagnosis in males, prepubertal females, women using hormonal contraceptives, and postmenopausal women 1

More Flexible Weight Criterion

• DSM-IV specified "less than 85% of expected weight"; DSM-5 uses the more flexible "significantly low body weight" language 1
• This allows clinicians to consider multiple factors including growth charts, BMI percentiles in youth, and clinical context 1

Clinical Implications of DSM-5 Changes

Increased Case Detection

• The lifetime prevalence of anorexia nervosa increased from 2.2% to 3.6% with DSM-5 criteria in population studies 5
• New cases identified under DSM-5 tend to have later age of onset (18.8 vs. 16.5 years), higher minimum BMI (16.9 vs. 15.5 kg/m²), shorter illness duration, and better prognosis 5

Diagnostic Heterogeneity

• The broadened criteria create a more heterogeneous patient population with varying severity and prognosis 5
• This underscores the importance of assessing severity beyond just BMI, including medical complications, psychiatric comorbidity, and functional impairment 5

Common Diagnostic Pitfalls

Distinguishing from Other Eating Disorders

• Bulimia nervosa: Both may involve binge eating and purging, but anorexia nervosa requires significantly low body weight 3, 4
• Avoidant/restrictive food intake disorder (ARFID): Weight loss occurs without body image disturbance or fear of weight gain 1
• Binge eating disorder: No compensatory behaviors and no significantly low weight 1

Medical vs. Psychiatric Weight Loss

• Anorexia nervosa is a differential diagnosis in any underweight patient, particularly young women 6
• The key distinguishing features are the psychological components: fear of weight gain, body image disturbance, and lack of recognition of the seriousness of low weight 6
• Medical causes of weight loss (inflammatory bowel disease, hyperthyroidism, malignancy) lack these psychological features 1

Overlapping Presentations

• Some patients with functional gastrointestinal disorders may restrict eating due to symptoms, but significant malnutrition is rarely a consequence of these disorders alone 1
• Patients with anorexia nervosa commonly develop delayed gastric emptying and delayed intestinal transit as physiologic consequences of malnutrition, which can confound the clinical picture 1