# Eating Disorders in Adolescents

## Introduction

Eating disorders are serious psychiatric illnesses with the highest mortality rate of any mental health condition. They affect approximately 2-5% of adolescents, with onset most commonly during adolescence. While historically associated with young White females, eating disorders occur across all genders, races, ethnicities, socioeconomic groups, and body sizes. Early identification and treatment significantly improve outcomes, yet the average delay from symptom onset to treatment is 3-5 years. Pediatricians are uniquely positioned to identify eating disorders early through routine growth monitoring, nutritional assessment, and psychosocial screening.

## Classification (DSM-5)

### Anorexia Nervosa (AN)

Anorexia nervosa involves restriction of energy intake leading to significantly low body weight relative to age, sex, developmental trajectory, and physical health; intense fear of weight gain or persistent behavior interfering with weight gain; and disturbance in body image or self-worth unduly influenced by body weight and shape. Subtypes include the restricting type and the binge-eating/purging type. BMI-based severity ranges from mild (BMI 17 or greater) through moderate (16-16.99), severe (15-15.99), and extreme (less than 15), though in children BMI percentile should be used.

### Bulimia Nervosa (BN)

Bulimia nervosa is characterized by recurrent episodes of binge eating (loss of control over eating) occurring at least once weekly for 3 months, accompanied by recurrent compensatory behaviors to prevent weight gain including self-induced vomiting, laxative or diuretic misuse, fasting, and excessive exercise. Self-evaluation is unduly influenced by body shape and weight. Body weight is often normal or above normal, so bulimia should not be ruled out based on weight.

### Binge Eating Disorder (BED)

Binge eating disorder involves recurrent binge eating episodes without regular compensatory behaviors. Episodes are marked by eating rapidly, eating until uncomfortably full, eating when not hungry, eating alone due to embarrassment, and feelings of disgust or guilt. It is often associated with overweight or obesity.

### Avoidant/Restrictive Food Intake Disorder (ARFID)

ARFID involves food avoidance or restriction that is not driven by body image concerns but leads to nutritional deficiency, weight loss, dependence on enteral or oral supplements, or psychosocial impairment. It is common in younger children and may be driven by sensory sensitivity, fear of choking or vomiting, or lack of interest in eating. ARFID often co-occurs with autism spectrum disorder and anxiety.

### Other Specified Feeding or Eating Disorders (OSFED)

OSFED encompasses clinically significant eating disorders that do not meet full criteria for AN, BN, or BED. It includes atypical anorexia nervosa (significant weight loss but not underweight), low-frequency bulimia, and night eating syndrome. Atypical AN is common in adolescents, and patients in larger bodies can have medically dangerous restriction that is missed because they do not appear anorexic.

<image>Diagnostic comparison chart of the major eating disorders (anorexia nervosa, bulimia nervosa, binge eating disorder, ARFID) showing key features, weight status, core psychopathology, and distinguishing characteristics for each diagnosis</image>

## Risk Factors and Screening

### Risk Factors

Biological risk factors include family history of eating disorders or mood disorders, premorbid anxiety, perfectionism, and genetic predisposition. Psychological risk factors include low self-esteem, body dissatisfaction, history of trauma or abuse, and comorbid depression, anxiety, or OCD. Sociocultural risk factors include weight stigma, diet culture, social media exposure promoting thin or muscular ideals, and participation in sports emphasizing leanness (gymnastics, wrestling, running, dance). LGBTQ+ youth have higher rates of disordered eating, and transgender adolescents may restrict in attempts to suppress pubertal development.

### Screening

Growth charts should be monitored at every well visit, as deceleration in weight gain (or height in younger children) may be the earliest sign. Body image, dieting, and eating behaviors should be assessed during adolescent visits (the "E" for Eating in the HEEADSSS assessment). The SCOFF questionnaire, validated for adolescents, asks five questions: whether the patient makes themselves Sick because they feel uncomfortably full, whether they worry they have lost Control over how much they eat, whether they have recently lost more than One stone (14 lbs) in a 3-month period, whether they believe themselves to be Fat when others say they are too thin, and whether Food dominates their life. A score of 2 or greater constitutes a positive screen.

## Medical Complications

### Cardiovascular

Bradycardia (heart rate less than 50 bpm) is the most common cardiac finding in AN and may progress to arrhythmias. Orthostatic hypotension is defined as a systolic drop greater than 20 mmHg or heart rate increase greater than 20 bpm on standing. QTc prolongation carries a risk of sudden cardiac death, and an ECG should be checked at presentation. Mitral valve prolapse can result from myocardial atrophy.

### Metabolic and Endocrine

Hypothalamic amenorrhea results from loss of GnRH pulsatility due to energy deficit and occurs even in atypical AN before significant weight loss. Bone loss from estrogen deficiency and nutritional deficits is particularly concerning because adolescence is the critical period for peak bone mass accrual, and lost bone may never be fully recovered. Low T3 syndrome (sick euthyroid) is an adaptive response to starvation and does not warrant thyroid hormone replacement. Electrolyte abnormalities include hypokalemia, hypophosphatemia, hypomagnesemia, and metabolic alkalosis from purging, along with hypoglycemia, elevated cortisol, low IGF-1, and growth hormone resistance.

### Gastrointestinal

GI complications include gastroparesis, constipation, and superior mesenteric artery (SMA) syndrome. Parotid gland hypertrophy and dental erosion result from purging. Esophageal tears (Mallory-Weiss) can occur from forceful vomiting.

### Hematologic

Pancytopenia from bone marrow suppression occurs in severe malnutrition, along with gelatinous transformation of bone marrow.

<image>Medical complications diagram showing a human body with labeled organ systems affected by eating disorders: brain (cognitive impairment, depression), heart (bradycardia, arrhythmia), bones (osteopenia), GI tract (gastroparesis, esophageal tears), endocrine (amenorrhea, hypothyroidism), metabolic (electrolyte derangements), and skin (lanugo, Russell sign)</image>

## Management

### Medical Stabilization and Hospitalization Criteria (Society for Adolescent Health and Medicine)

| Criterion | Threshold |
|-----------|-----------|
| Heart rate | <50 bpm daytime; <45 bpm nocturnal |
| Blood pressure | SBP <90 mmHg or orthostatic changes (SBP drop >20, HR rise >20) |
| Temperature | <35.6°C (96°F) |
| Weight | <75% median BMI for age and sex |
| Food intake | Acute food refusal |
| Syncope | Present |
| Electrolytes | Hypokalemia, hypophosphatemia |
| ECG | QTc prolongation, arrhythmias |
| Psychiatric | Suicidal ideation with plan or intent |

Indications for hospitalization include heart rate less than 50 bpm during the day or less than 45 bpm nocturnally, systolic blood pressure less than 90 mmHg or orthostatic changes, temperature less than 35.6C (96F), weight less than 75% of median BMI for age and sex, acute food refusal, syncope, electrolyte abnormalities (hypokalemia, hypophosphatemia), ECG abnormalities (QTc prolongation, arrhythmias), and suicidal ideation with plan or intent.

### Refeeding Syndrome

Refeeding syndrome is a life-threatening complication of nutritional rehabilitation in severely malnourished patients. It is caused by an insulin-driven intracellular shift of phosphorus, potassium, and magnesium when carbohydrates are reintroduced. It can cause cardiac failure, respiratory failure, rhabdomyolysis, seizures, and death. Prevention involves starting nutritional rehabilitation at an appropriate rate (current evidence supports higher caloric starts than traditionally used), monitoring electrolytes twice daily initially, supplementing phosphorus, potassium, and magnesium prophylactically, and maintaining cardiac monitoring.

### Evidence-Based Treatments

Family-Based Treatment (FBT, also known as the Maudsley approach) is first-line for adolescents with AN and BN. It empowers parents to take charge of refeeding and has the strongest evidence base. Cognitive-Behavioral Therapy enhanced (CBT-E) is effective for BN and BED in older adolescents. Adolescent-focused therapy (AFT) is an individual therapy alternative when FBT is not feasible. Nutritional rehabilitation with weight restoration is a primary treatment goal, with target weight based on premorbid growth trajectory rather than a specific BMI number. Medications have a limited role: fluoxetine is FDA-approved for BN, SSRIs may help with comorbid anxiety and depression but are not effective for core AN symptoms in underweight patients, and olanzapine may help with weight restoration and anxiety in AN.

### Monitoring During Recovery

Monitoring includes weekly weights (using blind weighing to reduce anxiety, with the patient weighed in a gown facing away from the scale), vital signs including orthostatics, electrolytes with phosphorus and magnesium during refeeding, menstrual recovery tracking (return of menses is a positive prognostic indicator), and DEXA scan if amenorrhea persists for more than 6-12 months to assess bone mineral density.

<image>Refeeding syndrome prevention protocol flowchart showing risk assessment, initial caloric prescription, electrolyte monitoring schedule, supplementation guidelines, and criteria for advancing caloric intake during nutritional rehabilitation</image>

## Clinical Pearls

Eating disorders occur in all body sizes -- a patient in a larger body can be medically unstable from restriction (atypical anorexia nervosa), and clinicians should not wait for a patient to appear underweight. Weight loss in a growing adolescent is always concerning, even if the starting weight was above average, because deceleration in expected growth warrants investigation. Bradycardia in an adolescent is not a sign of athletic fitness if there is concurrent weight loss or disordered eating -- it is a medical emergency. Family-Based Treatment is first-line for adolescent anorexia nervosa, and the family should be involved early. Clinicians should ask directly about eating behaviors and body image at every adolescent visit, as patients rarely volunteer this information.

## References

1. Golden NH, Katzman DK, Sawyer SM, et al. Position Paper of the Society for Adolescent Health and Medicine: Medical Management of Restrictive Eating Disorders in Adolescents and Young Adults. *J Adolesc Health*. 2015;56(1):121-125.
2. Lock J, Le Grange D. Treatment Manual for Anorexia Nervosa: A Family-Based Approach. 2nd ed. Guilford Press; 2013.
3. Campbell K, Peebles R. Eating Disorders in Children and Adolescents: State of the Art Review. *Pediatrics*. 2014;134(3):582-592.
4. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 5th ed. (DSM-5). American Psychiatric Publishing; 2013.