• Clinical science

Eating disorders

Abstract

Eating disorders are psychological conditions characterized by abnormal eating habits, disturbed body image, and, in some cases, weight loss. Adolescent girls and young women are most commonly affected, although the disorders also occur in males and older adults. Anorexia nervosa patients are preoccupied with their weight, body image, and a desire to be thin. Self-imposed restriction of calories, excessive exercising, or purging (e.g., laxative use) result in pronounced, and possibly fatal, weight loss. Bulimia nervosa is characterized by recurrent binge eating, followed by measures to compensate for overeating (e.g., self-induced vomiting), but does not lead to severe weight loss. Individuals with binge eating disorder have binge eating episodes but do not take measures to control their weight. Unlike in individuals with anorexia or bulimia nervosa, the fixation on body weight and shape is not as pronounced, and patients are often overweight. First-line treatment for all conditions is cognitive behavioral therapy. All conditions are associated with an increased risk of comorbidities (e.g., depression) and often have a chronic, relapsing disease course, though full remission can occur.

Anorexia nervosa

Epidemiology

  • Sex: > (10:1)
  • Age of onset: 10–25 years ; bimodal distribution at 13–14 years and 17–18 years
  • 12-month prevalence in adolescents: 0.2–0.4%

Etiology

The etiology of anorexia nervosa is multifactorial and not entirely understood. Several factors are thought to contribute to the development of the disease:

  • Genetic factors: There is a higher concordance of anorexia in identical twins than in fraternal twins.
  • Neurobiological factors: possible disorder of the endogenous reward system
  • Psychiatric factors: associated with OCD, anxiety disorders, and mood disorders
  • Psychosocial factors
    • Traumatization
    • Poor ability to handle/resolve conflicts
    • Difficulty establishing autonomy and gaining control (e.g., separation from parents)
    • High pressure careers and sports (e.g., ballet, modeling, gymnastics, wrestling )
    • Unrealistic standards of beauty

Diagnostic criteria (according to DSM V)

  • Significant deliberate reduction in body mass (as measured by BMI) using strategies that include restrictive eating, purging, and excessive exercise.
  • Fear of weight gain motivates compensatory behavior that promotes weight loss, even if the patient already has low body weight.
  • Body image disturbance
    • Excessive concern about weight and body shape, despite being considerably underweight
    • Lack of awareness of the seriousness of low body weight

Subtypes

  • Restricting type
    • No binge eating or purging over a 3-month period
    • Suggests weight loss achieved by excessive dieting, exercise, or fasting
  • Binge-eating/purging type
    • Presence of binge eating or purging over a 3-month period
    • Suggests weight loss achieved by vomiting, directive abuse, laxative abuse, or enemas

Severity based on BMI

  • Patients 2–20 years: BMI below the 10th percentile for sex and age is considered the threshold for being underweight.
  • Patients > 20 years
    • Mild: BMI 17–18.4 kg/m2
    • Moderate: BMI 16–16.99 kg/m2
    • Severe: BMI 15–15.99 kg/m2
    • Extreme: BMI < 15 kg/m2

Other clinical features

Diagnostics

Laboratory findings normalize following adequate treatment and weight gain!

Treatment

  • Psychotherapy (first-line)
  • Nutritional support
    • Monitor weight gain and provide nutritional support; usually through oral intake (hospitalization if necessary)
    • Indications for hospitalization:
    • Complication: refeeding syndrome
      • Pathophysiology: very rapid increase in daily food intake can cause massive insulin release → increased displacement of magnesium, potassium, and phosphate (shift from extracellular to intracellular)
      • Clinical features: edema, tachycardia (torsades de pointes), epileptic seizures, ataxia
      • Treatment: electrolyte substitution
      • Prophylaxis: : monitor electrolyte levels, limit initial dietary intake to 1000–1500 kcal/day
    • Contract governing medical treatment: agreement between the patient and caregivers on target weight development and daily number of meals (usually 3–5 meals/day, 500–1000 g weight gain/week)
  • Treatment of comorbidities (see “Prognosis” below)

Prognosis

Individuals with eating disorders may switch from one disorder to another or show merging of symptoms, especially following treatment of one disorder!

The risk of committing suicide is increased 20-fold in anorexic patients, and is most common in those suffering from depression!

References:[1][2][3][4][5][6][7]

Bulimia nervosa

Epidemiology

  • Sex: > (> 90% of affected individuals are young women)
  • Peak age: 20–24 years of age (late adolescence to early adulthood)
  • 12-month prevalence: ∼ 1–3% in young women

Etiology

Diagnostic criteria (according to DSM V)

All five criteria must be met for diagnosis:

  • Recurrent binge eating
  • Recurrent compulsive compensatory behavior to counteract weight gain
    • Most frequent: self-induced vomiting after binge eating
    • Laxative abuse
    • Transient starvation periods
    • Other weight loss measures
  • Binge eating and inappropriate compensatory behavior both occur at least once a week over a 3-month period.
  • Sense of self-worth pathologically influenced by perception of physical appearance (body weight and shape)
  • Symptoms do not exclusively occur during an episode of anorexia nervosa

Additional clinical features

Treatment

Treatment should be initiated as early as possible to avoid chronification:

Prognosis

Bulimia can transition to anorexia and vice versa!

References:[1][8][9][10]

Binge eating disorder

Epidemiology

  • Sex: >
  • Peak incidence: late teens to early 20s
  • Prevalence: ∼ 2–4%

Etiology

  • Multifactorial
    • Genetic factors (family history is common)
    • Family influences during childhood and adolescence )

Diagnostic criteria (according to DSM V)

  • Recurrent binge eating: eating a portion of food larger than average within 2 hours
  • Feeling of lack of control over amount of food consumed with at least three of the following properties:
    • Eating faster than normal
    • Eating until uncomfortably full
    • Eating large amounts when not hungry
    • Eating alone because of embarrassment regarding eating habits
    • Feeling of disgust and/or guilt after eating
  • Symptoms present at least 1/week for 3 months

Additional clinical features

Treatment

  • Psychotherapy (first-line): cognitive behavioral therapy (CBT)
  • Pharmacological therapy
    • May be added if CBT alone is ineffective
    • SSRI: helps to reduce binge eating impulse
    • Lisdexamfetamine or topiramate; (for patients who do not respond to treatment with SSRIs): reduces weight gain from binge eating and impulsive behavior

Prognosis

  • Chronic, relapsing disease course
  • More favorable prognosis than anorexia nervosa and bulimia nervosa
  • Increased risk of psychological comorbidities (e.g., depression)

Individuals with binge eating disorder suffer emotional distress due to their binge eating but do not try to control their weight!

References:[1][11]