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EATING DISORDERS (Anorexia Nervosa and Bulimia Nervosa)

Apr 11, 2023

Eating disorders

Eating disorders are serious and potential life-threatening. Anorexia nervosa disorder is characterized by severe restriction of food by a person. On the other hand, Bulimia nervosa is a cycle of binge eating followed by self-restricting behaviours like self-induced vomiting, excessive exercise or severe restriction of food. 

Eating disorders are an important part of the Psychiatry syllabus for NEET PG Preparation. Read this blog carefully to everything you need to know about Eating Disorders. 

ENT Residency

Anorexia Nervosa

  • Anorexia: Loss of appetite. But this is a misnomer because usually, the appetite in these patients is normal. More common in females - Females : Male : 10:1. Age of onset: 14 to 18 years. 

Clinical Features

  • Restriction of energy intake resulting in low body weight than normal.
    • ICD-11, Body Mass Index (BMI)
      • <18.5 kg/m3 in adults
      • Under 5th percentile in children and adolescents
  • Intense fear of weight gain or obesity. Disturbance of body image (under influence of body weight or shape on self-evaluation).
    • Inaccurately perceived to be normal or fat.
  • Amenorrhea
    • Previously a necessary criteria to diagnose. But it is removed from DSM-5 and ICD-11 as necessary criteria. Anorexia Nervosa can be diagnosed in absence of amenorrhea.
  • Peculiar behavior about food such as:
    • Hiding food. Trying to dispose of food in napkins. Spending time rearranging the food plate. Collecting recipes and preparing meals for others.
  • Delayed sexual development. Adults may show decreased interest in sexual activities.

Medical Complications Secondary to Starvation

  • Major
    • Hypothermia
    • Bradycardia
    • Hypotension
    • Lanugo hair (neonatal-like hair)
  • May have
    • Peripheral edema
    • QTC prolongation
    • Muscle atrophy
    • Brain atrophy
  • Other complications
    • Delayed gastric emptying
    • Constipation
    • Decreased bone mineral density

Endocrine changes

  • Decrease: LH, FSH, Estrogen, Testosterone, T4, T3.
  • Increase: Reverse T3, Cortisol.
  • Normal: TSH.

Types of Anorexia Nervosa

  • Restrictive
    • Seen in 50% of the patients. Restricting food intake. Do excessive exercises 
  • Binge Eating/Purging
    • Alternate attempts at rigorous dieting along with intermittent binge eating and purging episodes. Binge Eating/Purging is also seen in Bulimia Nervosa.

Q. What is Binge Eating?

  • Intake of large amounts of food in a short duration.
  • Associated with feeling of lack of self-control.

Q. What is Purging?

  • Patients may perform compensatory methods for excess calorie intake.
  • Includes
    • Vomiting
    • Use of Laxative, Diuretics, or Emetics
    • May do excessive exercises
  • If the patient performed repeated vomiting, it may lead to some complications:
    • Dental caries
    • Parotitis or salary gland swelling
    • Hypokalemic alkalosis
    • Electrolyte imbalance

Comorbid Psychiatric Disorders with Anorexia Nervosa

  • Most common: Depression.
  • Others: Social phobia, OCD (obsessive-compulsive disorder).

Course and Prognosis

  • High mortality rate, as high as any psychiatric illness.Mortality is six times more than the general population.
  • Cause of Death
    • Most common: Medical complications, low weight, and malnutrition. Suicide is another cause of death.
  • Predictors of Good Outcome
    • Shorter duration of illness in adolescents. Full restoration of weight in inpatient treatment. Maintaining weight in the first month after discharge (if a decrease in weight in the first month is seen, it is a bad predictor). Consuming a high energy density diet prior to discharge.


  • Patients are often secretive. They may deny their symptoms and resist the treatment. Hospitalization may be needed in:
    • Restoring nutritional status. Managing complications like
      • Dehydration
      • Electrolyte imbalances (↓Na, ↓K, ↓Cl).
  • Hospitalization criteria
    • Short term: 20% below the normal weight for height. Long-term psychiatric hospitalization: 30% below the normal weight for height.
  • Treatment goal
    • Nutritional rehabilitation and weight restoration
      At start 1500-1800 Kcal/day (divided meals), ↓ Gradually increased to 3500-4000 Kcal/day
    • Monitoring the Patient
      • To prevent self-induced vomiting - 2 hours after each meal. For Refeeding Syndrome
      • As diet is increased, patients may be habituated to eating more. Leads to refeeding syndrome.

Refeeding Syndrome (Signs and Symptoms)

If carbohydrates and sodium are reintroduced too rapidly. 

↑sed insulin secretion (Anti-natriuretic effect) and ↑ sodium leads to - ↑ECF volume . Carbohydrates stimulates intracellular Glucose-6-phosphate and Glycogen synthesis,  ↓ Phosphate, More intake of food than prior,  ↑ Metabolism (↓ Phosphate, ↓K, ↓Mg)

  • Thiamine deficiency and cardiac arrhythmias may occur. Cardiac arrythmias can occur.


  • Behavioral management
    • Praise for healthy eating habits.
    • Restriction of self induced vomiting.
  • Individual therapy. Family education


  • SSRIs may be beneficial. Antipsychotic: Olanzapine is showing promising results.
    • Promoting weight gain.
    • Reducing distressing psychological symptoms.

Bulimia Nervosa

  • Bulimia (Greek word): Ox Hunger. More common in females - Females : Male::10:1.
  • Age of Onset
    • Late adolescence and young adulthood. Slightly later than Anorexia Nervosa. 18-21 group.
  • Episodes of binge eating combined with inappropriate ways of preventing weight gain.

Clinical Features

  • Binge eating: Eating large amounts of food in a shorter time. Lack of control over eating. Followed by compensatory behavior to prevent weight gain, includes:
    • Purging behaviors
      • Vomiting. Use of Laxative, or Diuretics, or Emetics. 
      • May do excessive exercises
      • Fasting
  • Occurrence: 1/week for 3 months. May have
    • Fear of weight gain or obesity
    • Desire to lose weight
  • Normal weight or weight gain is seen.
  • Features Secondary to Purging
    • Enamel erosion
    • Dental caries
    • Parotitis or salary gland swelling
    • Russell’s Sign: Callus on knuckles
      This is usually due to the self-induced vomiting, the knuckles get injured by the teeth.
    • Hypokalemia
    • Hypochloremia 
    • Hyponatremia
    • Alkalosis 
    • Rarely: Gastric and esophageal tears.
  • All the secondary features to purging are also seen in Anorexia Nervosa (Binge Eating/Purging type). Most of the patients are sexually active as compared to Anorexia Nervosa. Some may have menstrual irregularities. Not secretive, open for treatment. Higher rates of recovery compared to anorexia nervosa. Mortality rate is also very low.


  • OPD treatment.
  • Psychotherapy
    • First line treatment - Cognitive Behavioral Therapy (CBT).
  • Pharmacotherapy
    • SSRIs - Fluoxetine showed better results.
    • Bupropion is contraindicated due to the increased risk of seizures.
      • Patients may have seizures due to loss of electrolytes.

Binge Eating Disorder (BED)

  • Most common eating disorder. More common in females - Females (1.75): Male (1), lesser than Anorexia Nervosa and Bulimia Nervosa. Episodes of binge eating but there is no compensatory behavior. There is a sense of lack of self-control.
  • Behavioral evidence of lack of self-control
    • Patients may eat more rapidly.
    • Eat even when not hungry.
    • Feel embarrassed or guilty after overeating.
    • May eat alone to hide the behavior.
  • Occurrence: 1/week for 3 months.
  • Weight: Overweight or obese range.


  • Psychotherapy
    • First line treatment: Cognitive Behavioral Therapy (CBT).
  • Pharmacotherapy
    • SSRIs - Maybe used. Recently, Lisdexamphetamine is approved by the FDA for short term treatment.
      • Helps in reducing weight and binge eating episodes. Long term safety and efficacy are yet to be proven.
  • BED was recently added in DSM-5 (most common). As per previous studies it was believed that Bulimia Nervosa is more prevalent than Anorexia Nervosa. But recent epidemiological studies have shown that Anorexia Nervosa has more prevalence.
Type of Eating DisorderLifetime Prevalence
Anorexia Nervosa2-4%
Bulimia Nervosa2%

Avoidant Restrictive Food Intake Disorder

  • There is avoidant and restriction for food intake. Newly added in both DSM5 and ICD-11.
  • Characteristics
    • Insufficient food intake due to:
      • Lack of interest in food. Avoiding based on sensory features of food. Perceived consequences of food.
    • Loss of weight or inability to gain weight
    • Nutritional deficiency
  • There is no disturbance of body image, as in Anorexia Nervosa.
  • Age of Onset
    • May develop in infancy or childhood. May persist in adulthood


  • Psychotherapy
    • Interaction with mother and infant. Educating and training the parents
  • Hospitalization required if there is:
    • Failure to thrive. Nutritional deficiencies.

And that is everything you need to know about Eating Disorders for Psychiatry preparation. For more informative and interesting posts like this, download the PrepLadder App and keep following our blog.

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