Eating disorders (EDs) are psychiatric conditions characterized by severe body dissatisfaction, overvaluation of a thin body ideal, and dysfunctional cognitive and weight control behaviors.
Anorexia nervosa (AN) typically affects 15 to 19-year-old girls and involves a significant overestimation of body size and shape, coupled with a relentless pursuit of thinness.
AN presents with an intense fear of becoming fat despite the patient being significantly underweight (often body weight <85% of expected).
Bulimia nervosa (BN) generally affects 10 to 19-year-old youth (chiefly females) and tends to emerge in later adolescence, sometimes evolving directly from preexisting AN.
BN is characterized by recurrent episodes of binge eating alternating with inappropriate compensatory behaviors, such as self-induced vomiting, misuse of laxatives or diuretics, fasting, or excessive exercise.
While AN involves extreme loss of weight, the weight of individuals with BN may fluctuate around a normal to moderately high baseline.
Epidemiology and Patient Profile
Feature
Anorexia Nervosa
Bulimia Nervosa
Typical Onset
Early to middle adolescence (15–19 years).
Later adolescence (10–19 years).
Personality Traits
Above-average intelligence, perfectionist, conflict-avoidant, and risk-aversive.
High impulsivity and frequent features of borderline personality disorder.
Psychiatric Comorbidities
High rates of anxiety, obsessive-compulsive symptoms, and emotional “numbness” to starvation.
Pronounced mood swings, depression, posttraumatic stress disorder (PTSD), and higher risk of suicidal ideation.
DSM-5 Diagnostic Criteria
Diagnostic Domain
Anorexia Nervosa
Bulimia Nervosa
Core Behaviors
Restriction of energy intake relative to requirements, leading to significantly low body weight.
Recurrent episodes of binge eating (eating large amounts with a sense of lack of control).
Cognitive Features
Intense fear of gaining weight or becoming fat, and severe disturbance in body weight/shape perception.
Self-evaluation is unduly influenced by body shape and weight.
Compensatory Acts
Persistent behavior interfering with weight gain despite being at a significantly low weight.
Amenorrhea (preceding weight loss in up to 30%), delayed puberty, osteopenia, and osteoporosis.
Irregular menses; osteopenia is generally less pronounced than in AN.
Differential Diagnosis
Clinicians must rule out medical conditions presenting with high catabolism, such as hyperthyroidism, occult chronic infections, and malignancies.
Malabsorption syndromes like celiac disease or inflammatory bowel disease can mimic the weight loss of EDs; however, eating in AN causes discomfort due to gastric atony rather than true malabsorption.
Endocrine disorders such as Addison disease mimic the symptoms of restrictive AN but distinctly present with hyperkalemia and hyperpigmentation.
Central nervous system anomalies, including craniopharyngiomas or Rathke pouch tumors, may cause weight loss and growth failure but present with signs of increased intracranial pressure.
Mitochondrial neurogastrointestinal encephalomyopathy (caused by a TYMP gene mutation) presents with gastrointestinal dysmotility, cachexia, and leukoencephalopathy, and is frequently misdiagnosed initially as AN.
Avoidant/restrictive food intake disorder (ARFID) mimics AN’s severe weight loss but lacks any underlying disturbance in body image or drive for thinness; the restriction is driven by sensory aversions or fears of choking.
Management Principles
The treatment of both AN and BN is ideally provided by an interdisciplinary team comprising a physician, nurse, registered dietitian, and mental health provider.
The approach should utilize the biopsychosocial model, framing the ED as a “maladaptive coping mechanism” and avoiding placing blame on the patient or the parents.
Nutritional Rehabilitation (AN):
The initial goal is to achieve steady weight gain (0.5–1 lb/week) by increasing energy intake by 100–200 kcal increments toward a target of approximately 90% of expected body weight.
Refeeding must proceed carefully, monitoring for refeeding syndrome (characterized by rapid drops in serum phosphorus, magnesium, and potassium) which can precipitate tachycardia, heart failure, and neurologic symptoms.
Fat content may initially need to be lowered to 15–20% to accommodate fat phobia, alongside calcium and vitamin D supplementation to address osteopenia.
Inpatient Medical Hospitalization (AN): Indicated for physiological instability, including a heart rate <50 beats/min, blood pressure <80/50 mm Hg, profound hypothermia (<36.1°C), severe electrolyte disturbances, or body weight <80% of healthy expected weight.
Psychotherapy:
Family-Based Treatment: The Maudsley approach is the only evidence-based treatment for AN in children and adolescents; it empowers parents to take an active, nurturing role in restoring their child’s eating habits without blame.
Cognitive-Behavioral Therapy (CBT): Focuses on restructuring thinking errors and establishing adaptive behaviors; it is highly effective in treating both AN and BN.
Dialectical Behavioral Therapy (DBT): Specifically useful for older adolescents with BN to challenge distorted thoughts and improve emotion regulation and mindfulness.
Pharmacotherapy:
Selective Serotonin Reuptake Inhibitors (SSRIs) lack evidence of efficacy for patients with AN who are at a low weight; nutritional restoration remains the primary treatment for depression in AN.
Conversely, SSRIs (such as fluoxetine at equivalent doses of >60 mg) are considered a standard element of therapy for BN and are highly effective in reducing binge-purge behaviors regardless of the presence of depression.
