Eating Disorders

Eating disorders are serious mental illnesses characterized by persistent disturbances in eating or eating-related behaviors that significantly impair physical health and psychosocial functioning. They have the highest mortality rate of any mental disorder.

Overview of Eating Disorders

Disorder	Core Feature	Weight Status	Binge Eating	Compensatory Behaviors
Anorexia nervosa (AN)	Restriction of energy intake relative to requirements	Significantly low body weight	Possible (binge-purge subtype)	Purging or other behaviors (in binge-purge subtype)
Bulimia nervosa (BN)	Recurrent binge eating + compensatory behaviors	Normal or overweight	Yes	Yes (vomiting, laxatives, fasting, excessive exercise)
Binge-eating disorder (BED)	Recurrent binge eating without compensatory behaviors	Overweight or obesity	Yes	No
Avoidant/restrictive food intake disorder (ARFID)	Restrictive eating without body image disturbance	Often low weight	No	No
Other specified feeding/eating disorder (OSFED)	Atypical presentations	Variable	Variable	Variable

Anorexia Nervosa (AN)

Anorexia nervosa is characterized by restriction of energy intake relative to requirements, leading to significantly low body weight, intense fear of weight gain, and disturbance in the experience of body weight and shape.

DSM-5 Diagnostic Criteria

Criterion	Description
A. Restriction	Restriction of energy intake relative to requirements, leading to significantly low body weight (less than minimally normal/expected)
B. Fear of weight gain	Intense fear of gaining weight or becoming fat, or persistent behavior that interferes with weight gain
C. Body image disturbance	Disturbance in how body weight/shape is experienced; undue influence on self-evaluation; lack of recognition of seriousness of low body weight

Specifiers:

Subtypes:

Subtype	Description
Restricting type	During last 3 months, weight loss主要通过 dieting, fasting, and/or excessive exercise; no binge eating or purging
Binge-eating/purging type	During last 3 months, has engaged in recurrent binge eating or purging behaviors (self-induced vomiting, laxatives, diuretics)

Severity (based on BMI):

Level	BMI (adults)
Mild	≥ 17.0
Moderate	16.0-16.99
Severe	15.0-15.99
Extreme	< 15.0

Epidemiology

Metric	Value
Lifetime prevalence	~0.5-2%
Female:male ratio	~10:1
Mean age of onset	~15-19 years
Standardized mortality ratio (SMR)	~5-6 (highest of any mental disorder)
Suicide rate	Elevated (second leading cause of death in AN)
Recovery rate (over 10 years)	~50-70%
Chronic course	~20%

Medical Complications

System	Complications
Cardiovascular	Bradycardia, hypotension, prolonged QTc, arrhythmias, mitral valve prolapse, cardiomyopathy (refeeding)
Endocrine	Hypothalamic amenorrhea, low T3 syndrome, growth hormone resistance, osteoporosis, stress fractures
Gastrointestinal	Delayed gastric emptying, constipation, superior mesenteric artery syndrome, pancreatitis
Renal	Dehydration, electrolyte abnormalities, pre-renal azotemia, nephrolithiasis
Hematologic	Leukopenia, anemia, thrombocytopenia
Integumentary	Lanugo, dry skin, acrocyanosis, hair thinning, Russell sign (from purging)
Neurologic	Generalized brain atrophy (reversible with weight restoration), peripheral neuropathy
Metabolic	Hypokalemia, hypophosphatemia (refeeding syndrome), hypomagnesemia

Refeeding syndrome:

• Potentially fatal metabolic disturbance when nutrition is reintroduced too rapidly
• Characterized by hypophosphatemia, hypokalemia, hypomagnesemia
• Can cause cardiac arrhythmias, respiratory failure, delirium, death
• Prevention: Slow refeeding, monitoring electrolytes, phosphate supplementation

Medical Monitoring

Parameter	Frequency
Weight, vital signs (orthostatic)	Weekly initially, then as indicated
Electrolytes (K, Na, Cl, CO2)	Weekly until stable, then as indicated
Phosphate, magnesium	Especially during refeeding (daily initially)
ECG	Baseline; repeat with electrolyte abnormalities
Bone density (DXA)	If amenorrhea > 6-12 months
Cardiac monitoring	With significant bradycardia or arrhythmias

Bulimia Nervosa (BN)

Bulimia nervosa is characterized by recurrent episodes of binge eating followed by inappropriate compensatory behaviors to prevent weight gain.

DSM-5 Diagnostic Criteria

Criterion	Description
A. Binge eating	Recurrent episodes of binge eating, characterized by both: (1) eating a large amount of food in a discrete period (2 hours) and (2) sense of lack of control
B. Compensatory behaviors	Recurrent inappropriate compensatory behaviors to prevent weight gain (purging, laxatives, fasting, excessive exercise)
C. Frequency	Binge eating and compensatory behaviors both occur at least once weekly for 3 months
D. Self-evaluation	Self-evaluation unduly influenced by body weight and shape
E. Exclusion	Not occurring exclusively during anorexia nervosa

Severity (based on compensatory behaviors per week):

Level	Frequency
Mild	1-3 episodes
Moderate	4-7 episodes
Severe	8-13 episodes
Extreme	14+ episodes

Epidemiology

Metric	Value
Lifetime prevalence	~1-2%
Female:male ratio	~8-10:1
Mean age of onset	~18-20 years
Usually normal weight or overweight	BMI typically in 18.5-30 range
Course	Chronic without treatment; waxing/waning

Medical Complications of Purging Behaviors

Behavior	Complications
Self-induced vomiting	Dental erosion (perimylolysis), parotid enlargement, esophageal tears (Mallory-Weiss), aspiration, calluses on hands (Russell sign), metabolic alkalosis, hypokalemia
Laxative abuse	Electrolyte disturbances, cathartic colon, dependence
Diuretic abuse	Electrolyte disturbances, dehydration
Excessive exercise	Overuse injuries, stress fractures, cardiac strain

Binge-Eating Disorder (BED)

Binge-eating disorder is characterized by recurrent episodes of binge eating without the regular use of compensatory behaviors.

DSM-5 Diagnostic Criteria

Criterion	Description
A. Binge eating	Recurrent episodes of binge eating with lack of control
B. Binge characteristics (3+ of 5)	(1) Eating more rapidly than normal; (2) Eating until uncomfortably full; (3) Eating large amounts when not hungry; (4) Eating alone due to embarrassment; (5) Feeling disgusted, depressed, or guilty after
C. Marked distress	Marked distress regarding binge eating
D. Frequency	At least once weekly for 3 months
E. Exclusion	Not associated with regular compensatory behaviors; not during AN or BN

Severity (based on binge episodes per week):

Level	Frequency
Mild	1-3 episodes
Moderate	4-7 episodes
Severe	8-13 episodes
Extreme	14+ episodes

Epidemiology

Metric	Value
Lifetime prevalence	~2-3%
Female:male ratio	~2:1 (more even than AN/BN)
Mean age of onset	~22-25 years
Associated with obesity	~50-70% of BED patients have BMI > 30
Course	Often chronic without treatment

Medical Complications

System	Complications
Metabolic	Obesity-related: insulin resistance, type 2 diabetes, metabolic syndrome, dyslipidemia, hypertension
Cardiovascular	Cardiovascular disease (associated with obesity)
Gastrointestinal	GERD, IBS, gallbladder disease
Musculoskeletal	Osteoarthritis (weight-bearing joints)
Sleep	Obstructive sleep apnea
Psychological	High rates of depression, anxiety, low quality of life

Other Specified Feeding or Eating Disorder (OSFED)

Presentation	Description
Atypical anorexia	All criteria for AN met except weight is not low (despite significant weight loss)
Bulimia nervosa (low frequency/limited duration)	BN criteria met but behaviors at lower frequency or duration
Binge-eating disorder (low frequency/limited duration)	BED criteria met but at lower frequency or duration
Purging disorder	Purging without binge eating
Night eating syndrome	Excessive evening/nighttime eating, with awareness and recall

Avoidant/Restrictive Food Intake Disorder (ARFID)

ARFID is characterized by restriction of food intake leading to nutritional deficiencies, weight loss, or psychosocial impairment, but without body image disturbance.

Feature	Description
Eating patterns	Limited food intake based on sensory sensitivity (texture, taste, smell), fear of aversive consequences (choking, vomiting), or lack of interest in food
Body image	No fear of weight gain or body image disturbance
Onset	Often childhood (but can persist into adulthood)
Comorbidity	Autism spectrum disorder, ADHD, anxiety disorders, OCD
Treatment	Exposure therapy, nutrition counseling, family-based treatment (children)

Risk Factors

Biological

Factor	AN	BN	BED
Heritability	~50-60%	~40-60%	~40-50%
Twin concordance (MZ)	~50%	~35%	~30%
Specific genetic loci	AN GWAS significant	Limited	Limited
Premorbid BMI	Lower	Higher	Higher

Psychological

Domain	Risk Factors
Personality	Perfectionism (especially AN), neuroticism, harm avoidance (AN), novelty seeking (BN), negative urgency
Cognitive	Body dissatisfaction, thin-ideal internalization, low self-esteem, cognitive rigidity
Temperament	Behavioral inhibition, negative affectivity, emotional dysregulation
Dieting	Early dieting is a strong predictor of onset

Environmental

Domain	Risk Factors
Family	Family history of eating disorders, parental eating/weight concerns, family dysfunction
Peer	Peer weight pressures, weight-related teasing/bullying
Cultural	Western beauty ideals, thinness pressure, social media, weight-based discrimination
Trauma	Childhood sexual abuse (especially BN, BED), physical abuse, neglect
Occupational/athletic	Ballet, gymnastics, wrestling, modeling (weight-sensitive industries)

Treatment

Anorexia Nervosa

Intervention	Description	Evidence
Nutritional rehabilitation	Weight restoration (0.5-1 kg/week inpatient; 0.25-0.5 kg/week outpatient); monitored refeeding	Essential for medical stabilization
Family-based treatment (FBT)	For adolescents; parents manage refeeding; three phases	First-line for adolescents
Enhanced CBT (CBT-E)	Adapted for AN; focuses on eating behaviors, weight, and maintaining mechanisms	Moderate evidence
Adolescent-focused therapy (AFT)	Individual therapy for adolescents with AN	Moderate evidence
Maudsley Anorexia Nervosa Treatment for Adults (MANTRA)	Specific to adult AN; motivational + cognitive remediation	Moderate evidence
Supportive clinical management	Medical monitoring, education, support	Moderate evidence
Olanzapine	Atypical antipsychotic for weight gain, anxiety	Limited evidence; sometimes used adjunctively

Levels of care:

Level	Criteria
Medical hospitalization	Medical instability (HR < 40, BP < 90/60, orthostatic changes, electrolyte disturbances, < 75% IBW, rapid decline)
Residential	Medically stable but needs 24-hour support for refeeding and therapy
Partial hospitalization	Needs daily structured programming but can sleep at home
Intensive outpatient	Needs multiple sessions per week
Outpatient	Medically stable, motivated, good support system

Bulimia Nervosa

Intervention	Description	Evidence
CBT-E (enhanced)	Addresses binge eating, compensatory behaviors, overvaluation of shape/weight	Strong; first-line for adults
Interpersonal psychotherapy (IPT)	Focus on interpersonal problems maintaining disorder	Moderate; alternative to CBT
Dialectical behavior therapy (DBT)	Emotion regulation, distress tolerance	Moderate
Fluoxetine (SSRI)	High-dose fluoxetine (60 mg/day); reduces binge-purge frequency	Strong; FDA-approved
Topiramate	Anticonvulsant; reduces binge-purge frequency	Moderate; side effect profile limits use
Guided self-help CBT	Structured workbook with minimal therapist contact	Moderate; for less severe cases

Binge-Eating Disorder

Intervention	Description	Evidence
CBT-E	Same protocol as BN; addresses binge eating	Strong; first-line
IPT	Focuses on interpersonal triggers	Strong; comparable to CBT
DBT	Intercepts binge episodes; distress tolerance	Moderate
Lisdexamfetamine	Stimulant prodrug; reduces binge episodes	Strong; FDA-approved
SSRIs	Moderate reduction in binge eating	Moderate
Topiramate	Significant reduction in binge eating	Moderate; side effects
Weight loss treatment	Behavioral weight loss + CBT	For BED with obesity

Special Populations

Children and Adolescents

• Family-based treatment (FBT) is first-line for adolescent AN
• Early intervention improves outcomes
• Medical complications more rapid in younger patients due to lower body reserves
• Growth and development monitoring essential

Males

• Underdiagnosed and undertreated
• May present with muscle dysmorphia (pursuit of muscularity rather than thinness)
• Higher rates of binge eating compared to AN/BN
• Greater stigma in seeking help

Athletes

• High-risk populations: endurance sports, aesthetic sports (gymnastics, figure skating), weight-class sports (wrestling, rowing)
• Female athlete triad: Disordered eating, amenorrhea, osteoporosis
• Relative energy deficiency in sport (RED-S)

Prognosis and Recovery

Outcome	AN	BN	BED
Full recovery (long-term)	~50-60%	~50-70%	~60-70%
Partial recovery	~20-30%	~20-30%	~20%
Chronic course	~15-20%	~10-20%	~10-20%
Mortality	~5-10% (highest psychiatric mortality)	~2-3%	~1-2%
Relapse rate	~30-50%	~30-40%	~30-40%
Recovery predictors	Early intervention, shorter illness duration, less severe weight loss	Motivation, early symptom reduction, psychosocial stability	Treatment adherence, social support

References

1. American Psychiatric Association. (2022). Diagnostic and Statistical Manual of Mental Disorders (5th ed., text rev.). Arlington, VA: APA.
2. Treasure, J., et al. (2020). Eating disorders. Lancet, 395(10227), 899-911.
3. Zipfel, S., et al. (2015). Anorexia nervosa. Nature Reviews Disease Primers, 1, 15074.
4. National Institute of Mental Health. (2023). Eating Disorders. NIMH.
5. Taylor, C. B., et al. (2020). Bulimia nervosa. New England Journal of Medicine, 382(5), 464-473.
6. Yager, J., et al. (2014). Practice guideline for the treatment of patients with eating disorders (3rd ed.). American Journal of Psychiatry, 171(7), 798-799.
7. Lock, J., & Le Grange, D. (2015). Treatment Manual for Anorexia Nervosa (2nd ed.). Guilford Press.
8. National Eating Disorders Association. (2023). Statistics and Research on Eating Disorders. NEDA.