Eating disorders are serious mental illnesses characterized by persistent disturbances in eating or eating-related behavior that impair physical health and psychosocial functioning. They have the highest mortality rate of any mental illness, largely due to medical complications and suicide. Anorexia nervosa, bulimia nervosa, and binge-eating disorder are the three primary diagnoses.

Sadness and grief — Eating disorders are serious mental health conditions characterized by disturbed eating behaviors and body image concerns. Source: Unsplash.

Anorexia Nervosa (AN)

Anorexia nervosa is characterized by restriction of energy intake relative to requirements, leading to significantly low body weight in the context of age, sex, developmental trajectory, and physical health; intense fear of gaining weight or becoming fat, or persistent behavior that interferes with weight gain; and disturbance in self-perceived weight or shape, undue influence of weight or shape on self-evaluation, or lack of recognition of the seriousness of low body weight.

Subtypes. Restricting type: no regular binge eating or purging. Binge-eating/purging type: regular binge eating or purging behavior (self-induced vomiting, misuse of laxatives, diuretics, or enemas).

Medical complications. Starvation affects every organ system. Cardiovascular: bradycardia, hypotension, prolonged QT interval, arrhythmias, sudden death. Endocrine: amenorrhea, low estrogen or testosterone, osteoporosis, growth hormone resistance and low IGF-1, sick euthyroid syndrome, hypercortisolism. Gastrointestinal: delayed gastric emptying, constipation, superior mesenteric artery syndrome. Hematologic: mild anemia, leukopenia, thrombocytopenia. Renal: dehydration, electrolyte disturbances, renal calculi. Neurologic: brain atrophy (partially reversible with weight restoration), peripheral neuropathy. Dermatologic: lanugo (fine downy hair), dry skin, hair loss, nail brittleness. Refeeding syndrome: when malnourished patients are reintroduced to nutrition, rapid shifts in electrolytes (phosphate, potassium, magnesium) and fluid can cause cardiac arrhythmias, respiratory failure, and death — it requires close monitoring.

Epidemiology. Lifetime prevalence is 1–2% in women and 0.1–0.3% in men. Onset is typically in mid-adolescence (14–18 years). The female-to-male ratio is 10:1. Recovery rates are 30–60%, with approximately 20% remaining chronically ill. Mortality is approximately 5% per decade, the highest of any psychiatric disorder.

Treatment. First-line for adults: cognitive behavioral therapy for eating disorders (CBT-ED) or Maudsley anorexia nervosa treatment for adults (MANTRA). First-line for adolescents: family-based treatment (FBT, also known as the Maudsley approach) — parents play an active role in restoring weight. Medical stabilization and weight restoration are the initial priorities. Nutritional rehabilitation typically targets 1–2 kg of weight gain per week in inpatient settings. No medication is FDA-approved for AN; weight restoration is the primary intervention. Olanzapine may help with weight gain and reduce anorexic cognitions.

⚠ Clinical Correlation

Refeeding syndrome is a potentially fatal complication of nutritional rehabilitation in severely malnourished patients. During starvation, intracellular phosphate, potassium, and magnesium are depleted. With refeeding, insulin secretion causes rapid intracellular shift of these electrolytes, leading to hypophosphatemia, hypokalemia, and hypomagnesemia. Consequences include cardiac arrhythmias, respiratory failure, rhabdomyolysis, seizures, and delirium. Prevention: starting calories at a conservative level (800–1200 kcal/day), careful electrolyte monitoring and replacement, and supplementing thiamine (to prevent Wernicke encephalopathy). Patients at highest risk: those <70% of ideal body weight, with rapid weight loss, minimal nutritional intake for extended periods, or electrolyte abnormalities at baseline.

Bulimia Nervosa (BN)

Bulimia nervosa is characterized by recurrent episodes of binge eating (eating, in a discrete period of time, an amount of food that is definitely larger than what most individuals would eat in a similar period under similar circumstances, with a sense of lack of control over eating during the episode) and recurrent inappropriate compensatory behaviors to prevent weight gain (self-induced vomiting, laxative or diuretic misuse, fasting, excessive exercise). The binge eating and compensatory behaviors both occur at least once a week for three months. Self-evaluation is unduly influenced by body shape and weight. The disturbance does not occur exclusively during episodes of anorexia nervosa.

Medical complications. Electrolyte disturbances due to vomiting: hypokalemic, hypochloremic metabolic alkalosis. Dental effects: perimylolysis (erosion of tooth enamel from gastric acid), dental caries, parotid gland hypertrophy (chipmunk cheeks). Russell sign: calluses or abrasions on knuckles from self-induced vomiting. Gastrointestinal: Mallory-Weiss syndrome (esophageal tears), esophageal rupture (Boerhaave syndrome), gastric dilatation or rupture, chronic constipation from laxative abuse. Ipecac syrup (used to induce vomiting) causes cardiomyopathy.

Epidemiology. Lifetime prevalence is 1–2% in women and 0.1–0.5% in men. Onset is typically in late adolescence to early adulthood (16–22 years). Recovery rates are approximately 50–70%. Mortality is 1–3%.

Treatment. CBT-ED is first-line, specifically enhanced cognitive behavioral therapy (CBT-E). It addresses the maintaining mechanisms of the disorder — overvaluation of weight and shape, dietary restraint, and binge-purge cycles. The selective serotonin reuptake inhibitor fluoxetine at high dose (60 mg daily) is FDA-approved for BN and reduces binge-purge frequency. It is most effective when combined with CBT.

Binge-Eating Disorder (BED)

BED is characterized by recurrent episodes of binge eating without inappropriate compensatory behaviors. Binge episodes occur at least once a week for three months and are associated with eating more rapidly than normal, eating until uncomfortably full, eating large amounts without physical hunger, eating alone due to embarrassment, and feeling disgusted, depressed, or guilty after overeating. Marked distress about binge eating is required.

Medical complications. BED is associated with obesity, metabolic syndrome, type 2 diabetes, cardiovascular disease, and sleep disorders. However, many individuals with BED are not overweight — the disorder occurs across weight categories.

Epidemiology. BED is the most common eating disorder, with a lifetime prevalence of 2–3% in the general population and 5–10% among individuals seeking weight-loss treatment. It affects women and men more equally than AN or BN (female-to-male ratio approximately 3:1). Onset is typically in late adolescence or early adulthood but can occur later.

Treatment. CBT-ED is first-line, with the strongest evidence base. Interpersonal psychotherapy is also effective. The stimulant prodrug lisdexamfetamine is FDA-approved for moderate to severe BED and reduces binge frequency. Antidepressants (SSRIs) and the anticonvulsant topiramate also reduce binge eating.

★ Key Concept

Weight stigma — negative attitudes and beliefs about people with higher body weight — is pervasive in healthcare, media, and everyday life. It causes direct harm: patients who experience weight stigma are less likely to seek medical care, more likely to delay preventive services, and receive poorer quality care. Weight stigma also contributes to the development of eating disorders — body dissatisfaction, dietary restraint, and binge eating are linked to internalized weight bias. Eating disorder treatment must be weight-inclusive, focusing on health behaviors rather than weight as a metric. Health at Every Size (HAES) approaches emphasize intuitive eating, physical activity for well-being, and body acceptance.

Other Specified Feeding or Eating Disorders (OSFED)

OSFED includes clinically significant eating disorders that do not meet full criteria for AN, BN, or BED. Examples: atypical anorexia nervosa (normal weight despite significant weight loss), purging disorder, and night eating syndrome. OSFED is common and not less severe — it warrants the same clinical attention.

Summary

Eating disorders are serious, life-threatening mental illnesses affecting individuals across weight categories, genders, and cultures. Anorexia nervosa carries the highest mortality of any psychiatric disorder and requires careful medical monitoring during refeeding. Bulimia nervosa is characterized by the binge-purge cycle, treatable with CBT and SSRIs. Binge-eating disorder, the most common eating disorder, is effectively treated with CBT and medication. Early intervention improves outcomes. All eating disorders benefit from multidisciplinary care involving medical, nutritional, and mental health professionals.