Eating disorders like anorexia nervosa, bulimia nervosa, and the binge eating disorder are no rare diseases in psychiatric and psychosomatic medicine. Exact knowledge of pathogenesis and symptoms of these diseases, which mostly affect young women, is crucial for a correct diagnosis and accurate therapy. This article is supposed to help you to correctly diagnose the different eating disorders in both the second state exam and in professional life later on.
Anorexic emaciation in a hysteric General Collections Keywords

Picture: “Anorexic emaciation in a hysteric General Collections Keywords: Psychiatry” by Welcome Images. License: CC BY 4.0

Definition, Epidemiology and Etiology of Eating Disorders

All eating disorders have in common a disturbance in body perception (body image disturbance): The patients, who mainly are young, adolescent women, consider themselves too thick despite being, in reality, of normal weight or even underweight. According to the current ideal of beauty in society, being slim is idealized almost pathologically. To avoid weight gain and to reduce weight, measures like fasting, physical strain, and laxatives are used, which not scarcely result in organic consequential diseases.

While anorexia nervosa is diagnosed in 0.5 – 1 % of the 15 – 25 year-old-women in the normal population (peak at 14th and 18th year of life), prevalence in risk groups (ballet dancers, athletes, models) amounts to 7 %. Also, it more frequently occurs in higher social classes.

With a prevalence of 3 – 4 %, bulimia nervosa is more frequent than anorexia and typically occurs at an age of 18 to 35. Bulimia literally means “ox/bull hunger” since ravenous hunger attacks play an important role in this disease. Also, men can suffer from eating disorders, but with a percentage of 10 – 15 % of the affected people, they only represent a minority.

The binge eating disorder has a prevalence of 2 – 5 % throughout the population, whereas it is estimated that 20 – 50 % of overweight patients are affected.

Overall, eating disorders are far more frequent in Western industrial nations than in developing countries, which suggests an association with the oversupply of food.

Anorexia and bulimia can merge or occur in combination. In this case, one speaks of bulimarexia.

The causes of all eating disorders cannot be tracked back to a single event, but consist of the interaction between biological, psychic, and social factors, the details of which are partially not clear. Twin studies show that, among others, genetic factors play a role.

Anorexia Nervosa

Classification of Anorexia Nervosa

Literally, “anorexia” means “loss of appetite”, which, strictly speaking, does not apply to the disease since the patients experience (partially very strong) hunger sensations, but deny them and try to suppress them.

According to the DSM-IV, two kinds of anorexia nervosa can be distinguished:

  • Purging-type
  • Non-purging type (or restrictive type)

The non-purging type is characterized by excessive hungering, while, at the purging-type (also called bulimic type), additionally, medicament abuse (laxatives, diuretics) and induced vomiting are used to reduce weight. The distinction of this type to bulimia is that eating attacks which are typical for bulimia are absent in this case.

In the ICD-10, anorexia nervosa can be found under the eating disorders (F 50) and is classified as F 50.0.

Pathogenesis of Anorexia Nervosa

The causes for the development of anorexia are complex. The risk to become diseased of anorexia nervosa is genetically determined and occurs more frequently in relatives of anorexics. Also, anorexia nervosa occurs as comorbidity at obsessive-compulsive disorders, affective disorders, or impulse-control disorders. Psychosocial factors are of great significance as well and are intensified further by pressure exerted by the family of the affected person or by disturbed family relations.

Also, individual personality features play an important role. Thus, anorexics often are very achievement-oriented and perfectionistic. Also, rigidity and low self-esteem are attributed to them. They deny their identity as a woman (or man) and show an anankastic-avoiding defense style. Psychological causes are considered to be based on the increased need for control and the wish for autonomy and self-determination.

Additionally, there is the euphoriant effect of fasting periods of at least three days, which makes anorexia nervosa similar to addictive disorders.

Note: Anorexia nervosa has a high risk for chronification and mortality!

Symptoms of Anorexia Nervosa

The characteristic symptom of anorexia nervosa is weight phobia, the fear of weight gain, along with a body image disturbance: The patients live in constant fear to gain weight. Still, they consider themselves too thick despite being underweight and often find their own body disgusting. Also, they lack disease awareness. Thus, compliance is very little or not present at all, especially at the beginning of treatment.

For this disease, the subject of food determines everything in the life of the patients. Mostly, a strict diet is adhered to, which only allows a limited calory intake per day or forbids certain food. Also, complete food refusal is possible. This way, extreme weight loss occurs, which – on average – amounts to 45 % of the original weight.

Two images of an anorexic female patient in a French medical journal Nouvelle Iconographie de la Salpêtrière vol 13, published in 1900.

Picture: “Two images of an anorexic female patient in a French medical journal Nouvelle Iconographie de la Salpêtrière vol 13, published in 1900.” by Georges Gasne. License: Public Domain

Due to the disturbed hormonal household, menstruation pauses, which is called amenorrhea. Mostly, it is accompanied by the beginning of the disease, but can also set in at an earlier stage.

The patients have a distinct need for movement and are motoricly overactive. Thus, often sports like jogging or long hikes are performed despite weakness and emaciation as a consequence of malnutrition to further reduce weight and cope with inner unrest.

Diagnostics of Anorexia Nervosa

In order to diagnose anorexia, extensive anamnesis and physical examinations have to be conducted. Also, body weight 15 % under the normal weight for age and height has to be detected. Alternatively, the body mass index (BMI; Quetelet index) can be used, which has to be under 17,5 kg/m2.

Note: BMI = body weight in kg / height in (m)2
Graph of body mass index showing the various divisions.

Picture: “Graph of body mass index showing the various divisions.” by InvictaHOG. License: Public Domain

Further ICD-10 diagnostic criteria are: body image disorders, endocrinological disorders (amenorrhea), and self-induced weight loss via fasting. Additionally, either vomiting, laxatives/diuretics or motoric overactivity accurs. If the disease begins before puberty, retardation of physical development can be observed.

Differential Diagnostics of Anorexia Nervosa

In order to diagnose anorexia, organic causes like tumors, gastro-intestinal disease (e.g. Morbus Crohn), or diabetes mellitus have to be excluded.

Anorectic reactions have to be delimited from anorexia nervosa. Those are temporary, non-chronic symptoms. For example, they can occur after stressful situations or at psychotic disorders (e.g. schizophrenia). An obvious sign that no anorexia nervosa is present is the absence of weight phobia and body image disorders.

Therapy of Anorexia Nervosa

The major part of therapy consists of psychotherapy with behavior, individual, family, body, and movement therapy. Mostly, hospitalization is advisable to get the patients out of the environment which promotes the disorder. During hospitalization, the goal of therapy is to gain ca. 500 g (max. 1000 g) of weight per week. This is controlled by regular weighing. With initially strict food plans and later self-determination of food intake, a normal eating behavior should be restored.

During the acute stage of anorexia nervosa, force-feeding with parenteral electrolyte solutions and a nasoduodenal tube with a stay at an intensive care station can be necessary. In depressive patients, short-term application of antidepressants or neuroleptics can be reasonable. However, those are not suitable for long-term therapy.

Due to the low disease awareness of the patients, therapy often is very difficult and spans over a period of several months to years.

Complications of Anorexia Nervosa

Anorexia has an effect on the whole life of the patients: They often withdraw into themselves, want to be independent of others, and more or less deliberately slide into social isolation (splendid isolation). Half of the patients suffer from depression as psychic comorbidity. Also, organic consequences are possible: malnutrition, excessive hungering, hyperactivity, and medicament abuse can harm the whole organism (dystrophy). In the following, several consequential phenomena are listed:

  • Electrolytes: disturbed electrolyte household with renal damages, edema, dehydration
  • Gastrointestinal tract: caries, obstipation, nausea, stomach pain, swollen parotid glands
  • Cardiovascular system: bradycardia, hypokalemia (due to vomiting or laxative/diuretic abuse), hypotension, hypothermia
  • Blood count: anemia, thrombocytopenia, hypoplasia of bone marrow
  • Skin: dry and leprose, alopecia, lanugo hair
  • Endocrine: amenorrhea (♀), loss of libido and potency (♂), hypogonadism, increased cortisol levels, hypoglycemia, osteoporosis, decreased levels of thyroid hormones
  • Central and peripheral nervous system: polyneuropathy (due to vitamin-b deficiency), concentration disorders, expansion of cortical sulci

Partially, the resulting damages are irreversible and can lead to death in 15 % of the patients.


Bulimia Nervosa

Classification of Bulimia Nervosa

In the ICD-10, bulimia nervosa can be found under the eating disorders (F 50) and is classified as F 50.2.

Pathogenesis of Bulimia Nervosa

As for anorexia, the causes of bulimia are also complex. The influence of genetic factors seems to play a role, but is not completely clear. On the biological level, studies show that bulimia patients have a disorder in saturation regulation.

Patients often show distinct self-insecurity and a high need for appreciation. They are affectively instable and have problems in coping with inner tensions. Thus, condescending statements concerning body weight or body shape can be the cause for separation situations.

Also, the lack of impulse control is an important factor in the development of bulimia nervosa. The defense style of bulimics can be described as dramatic-impulsive.

Traumatic experiences (e.g. sexual abuse) can also influence pathogenesis of bulimia.

Symptoms of Bulimia Nervosa

Characteristic symptoms for bulimia nervosa are recurring ravenous hunger attacks along with the intake of large amounts of high-caloric food, which, following the intake, are removed from the body via counter-regulatory measures (self induced vomiting, laxatives, diuretics, thyroid gland preparation) to avoid the thickening effect. After an eating attack, shame and feelings of guilt rise.

In contrast to anorexics, the patients mostly are of normal weight (sometimes slightly overweight) and do not suffer from a body image disorder, but exhibit high psychological strain. They (mostly) are conscious of their disturbed eating behavior and are ashamed of it, which is why they try to hide it. Simultaneously, they suffer from constant fear of weight gain, whereas their weight does not constantly decrease (like at anorexia), but remains relatively stable (fluctuations of +/- 5 kg are possible).

While vomiting is aelf-induced at the beginning of the disease, reflectory vomiting can develop in the course of the disease.

80 % of the patients show psychic comorbidities like e.g. depressive upset, fear, and suicidality.

Diagnostics of Bulimia Nervosa

Often, the only difference between bulimia and anorexia is the criteria of underweight, which is mostly not present at bulimics.

According to ICD-10, the following criteria have to be present to diagnose bulimia: eating attacks, pathological fear of becoming overweight, constant preoccupation with greed for food, and avoidance of thickening effects of food via vomiting, medicament abuse (laxatives, diuretics, thyroid preparation), or occasional fastening. Often, anorexia nervosa can also be found when investigating the medical history of the patients.

In addition to the diagnosis, extensive anamnesis has to be performed and a physical examination has to be conducted.

Differential Diagnostics of Bulimia Nervosa

Psychiatrically, bulimia is to be distinguished from other eating disorders. The crucial feature for differentiation from anorexia is the characteristic of underweight which is not present in bulimics. Like at anorexia, organic diseases have to be excluded (see above).

Therapy of Bulimia Nervosa

First-resort therapy is psychotherapy, more precisely, cognitive behavioral therapy. At this, at least 25 sessions (at least once a week) should be held. For young patients, including the family is reasonable. The goal is to normalize eating behavior and avoid eating attacks. Furthermore, self-esteem has to be strengthened, while the fear of gaining weight has to be decreased.

Concerning medicaments, tricyclic antidepressants, selective serotonin reuptake inhibitors (SSRI) like e.g. fluoxetine are suitable, while monoaminoxidase inhibitors are useful for treating depressive coexisting symptoms and relapse prophylaxis.

Should ambulant therapy fail, or in case of self-injuring behavior or increased risk of suicidality, stationary therapy has to be initiated.

Complications of Bulimia Nervosa

Similar to anorexia, organic consequential damages can result from malnutrition or malnourishment. A particularly frequent complication is dental caries which is caused by vomiting and laxative abuse.

Oral Manifestation of Bulimia.

Picture: “Oral Manifestation of Bulimia.” by Jeffrey Dorfman. License: CC BY-SA 3.0

Also, the parotid glands are often swollen. Due to self-afflicted vomiting, lesions on the back of the hand can be found in some cases (“Russell’s sign”).

Russell’s Sign on the knuckles of the index and ring fingers.

Picture: “Russell’s Sign on the knuckles of the index and ring fingers.” by Kyukyusha. License: Public Domain

Not scarcely, secondary amenorrhea result from the eating disorder.

Patients with additional diabetes mellitus often consciously omit insulin consumption to excrete more glucose via the kidney (“renal vomiting”). This leads to problems in the adjustment of diabetes with the risk for consequential diseases.

Binge Eating Disorder

Classification and Symptoms of Binge Eating Disorder

In ICD-10, the binge eating disorder itself cannot be found and has to be classified as “eating attacks at other psychic disorders” (F 50.4).

Just like at bulimia, recurring ravenous hunger attacks with eating attacks occur at the binge eating disorder. However, vomiting of food that has already been ingested does not occur.

In contrast to anorexia and bulimia, the patients are mostly overweight or already obese. One third of all cases are men.

Diagnostics and Differential Diagnostics of Binge Eating Disorder

To diagnose binge eating disorder, the following criteria have to be present according to DSM-IV.

  • Repeated eating attacks with accompanying loss of control, which has to occur on at least two days per week over a course of at least six months.
  • Distinct psychological strain for the patients
  • Three of the following symptoms which occur along with the eating attacks: quicker eating than normal, eating until unpleasant saturation feelings occur, eating alone out of embarrassment, eating large amounts without being hungry, feelings of disgust or guilt after eating.
  • No regular inappropriate compensatory behavior (hunger, laxative/diuretics abuse, hyperactivity)

The binge eating disorder has to be delimited from bulimia. At both diseases, episodes of eating attacks occur with consumption of high-caloric food. However, the subsequent attempt to get rid of these calories via vomiting or via other measures is absent at binge eating disorder.

Therapy of Binge Eating Disorder

It is important to treat the symptoms, the psychic complaints, and comorbidities of the disease. Those are, firstly, eating disorders and possibly present obesity and, secondly, decreased feeling of self-esteem, depressions, and social fears.

Just like for the other eating disorders already mentioned, treatment is attempted via cognitive behavior therapy. Concerning medication, antidepressants (SSRI) can be used.

Complications of Binge Eating Disorder

Due to the frequently massive influx of high-caloric food, organic subsequent diseases can occur. Among others, there is the risk of premature arteriosclerosis, the development of diabetes mellitus or fat metabolism disorders and hypertension.

Also, degenerative states like arthrosis, connective tissue weakness, and complaints at the spine can result from binge eating disorder.

Symptoms of Eating Disorders in an Overview

Anorexia Nervosa Bulimia Nervosa Binge Eating Disorder
Underweight (decreasing) Normal weight (fluctuating) Overweight (increasing)
Goal: weight loss Goal: no weight gain Low fear of weight gain
Control compulsion Control loss Control loss
No psychological strain High psychological strain Psychological strain
Denial Shame and feelings of guilt Shame and feelings of guilt
Bad compliance Good Compliance Intermediate compliance

Popular Exam Questions Concerning Eating Disorders

The correct answers can be found below the references.

1. Bulimia nervosa mostly occurs in women in the ages of 18 to 35 years. Which symptom is not typical for this disease?

  1. High psychological strain of the patients
  2. Feeling of control loss
  3. Shame and feelings of guilt due to the disturbed eating behavior
  4. Bad compliance in therapy of the disease
  5. Repeated episodes of eating attacks with subsequent counter-regulatory measures

2. Case example: A 17-year-old student visits her family doctor due to increasing concentration problems and decreased performance. In physical examination, he determines that the patient is extremely emaciated. At a height of 1.60 m, she only weighs 44 kg. Upon enquiry, the patient, however, states that she feels well except for decreased performance. She experiences her physical state as normal. Furthermore, she requests her doctor to help her quickly become productive in school again. Which disease matches her symptoms?

  1. Binge eating disorder
  2. Anorexia nervosa
  3. Diabetes mellitus
  4. Hypothyreosis
  5. Bulimia nervosa

3. Anorexia is often accompanied by organic consequential diseases. Which of the following symptoms does not apply to anorexia nervosa?

  1. Alopecia
  2. Amenorrhea
  3. Hypokalemia
  4. Osteoporosis
  5. Decreased cortisol levels
Lecturio Medical Courses


Hoffmann, Hochapfel: Neurotische Störungen und Psychosomatische Medizin, 8. Auflage (2009) – Schattauer

Möller, H.-J., Laux G., Deister A.: Duale Reihe Psychiatrie und Psychotherapie, 4. Auflage (2009) – Thieme Verlag

Uexküll: Psychosomatische Medizin, Modelle ärztlichen Denkens und Handelns, 6. Auflage (2008) – Elsevier (Urban & Fischer)

Correct answers: 1D, 2B, 3E

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