Eating Disorders

Original article by Tom Leach | Last updated on 16/5/2014
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Anorexia Nervosa

Introduction

This is a psychological disorder, in which there is a relentless pursuit of thinness.
Anorexia is significant as it has a very high mortality rate:
  • 1/3 of patients make a complete recovery
  • 1/3 make only partial recovery and have many relapses
  • And approximately 10-25% of patients will die. This can be from suicide, pneumonia or hypokaleamia (leading to arrhythmias).
 

Epidemiology and Aetiology

  • Affects 1% of the population
  • Most commonly affects girls (10:1)
  • Incidence is rising in boys
  • Typically affects intelligent, diligent and highly motivated individuals – they must be perfectionists to be able to have the willpower to avoid eating.
  • Usually, patients come from happy families with little conflict – it is not an ‘attention seeking’ reaction to a ‘broken home’.
 

Features

The typical patient is a 14-15 year old girl. Usually in individuals who try to lose weight through calorie restriction, the limitation is short lived, either as the target weight is achieved, or the individual is unable to put up with the hunger!
In anorexia, people are able to put up with these urges and dramatically restrict food intake. There may be several or all of the following:
Overestimation of actual weight and body size – the discrepancy between actual and perceived weight increases as weight reduces.
  • Usually the girl will deny any weight loss, and disagree that she is too thin.

Phobia of normal body size and weight

Methods of reducing weight:

  • Restricting calorie intake
  • Over-exercise
  • Use of laxatives
  • Vomiting
  • Use of diuretics

Very low body weight

  • There is a ‘critical weight’ (usually around 48Kg) below which amenorrhoea will occur. If the girl is not completely through puberty, she may regress to a pre-pubertal state

The control of weight may give the patients a sense of power – puberty can be a difficult time of maturity, when many patients feel they are ‘losing control’ of their local environment. Anorexia gives control over weight which may be comforting

Obsession and pre-occupation with food and cooking – many girls take up cooking as a hobby, although never eat any of their own food

 

Clinical effects

The state of starvation may result in:
  • Low metabolic rate
  • Cold peripheries
  • Bradycardia
  • Alopecia
  • Osteopenia
  • Vitamin deficiencies & electrolyte disturbances
  • Amenorrhoea
  • Lanugo hair – fine downy hair that may appear on the body
  • Skin changes
  • Falsely low T3 level – giving appearance of hypothyroidism
  • Low plasma proteins
  • Ankle oedema
  • Urine
    • LH and ↓FSH
  • Associated with:
 
Physical appearance
Girls may typically wear large baggy clothes, and try to cover their faces and body.
It is believed that the popular culture of attractiveness being associated to thinness is partly to blame for many cases of anorexia.
 

Management

There are several aspects to management
  • Treat the psychological disorder
  • Encourage weight gain
  • Alter behaviours that lead to the development of anorexia
 
Parents should be involved right from the start, and there is usually parental counselling to help get across the seriousness of the situation.
Patients should be managed with outpatient hospital appointments involving a psychiatrist and a paediatrician, as well as other relevant staff (e.g. psychologist, support workers etc).
Weight gain is the most important part of treatment.
A simple technique often employed is the use of a contract. The patient is encouraged to enter into an agreement of weight gain / maintenance, and simple targets are set. The weight gained and not the eating habits are recorded, and usually the target is around 500g per week. If the target is not met, then hospital care will be required.
  • Only a small percentage of girls will continue to lose weight after admission. In these cases, tube feeding may be used.
  • On admission, the patient is usually fed 2000 calories per day. This is not usually in big meals, as these can cause difficulties.
  • Once a normal weight has been achieved, a more psychotherapeutic level of care is adopted. Signs that indicate a good prognosis include:
  • Good relationship with the parents
  • Ability to discuss previous suppressed emotional difficulties – usually around pressures of adolescence, growing up and relationships.
 
Drug therapy (e.g. SSRI’s) are not effective
 

Bulimia Nervosa

Bulimia is closely related to anorexia, and is categorised by some as a feature of anorexia, not a separate condition.  Typically patients may be slightly reduced or normal weight, although sometimes they may be overweight.
 

Epidemiology

  • More common than anorexia
  • More common in girls
  • Prevalence is increasing
  • Typically affects older teenagers than anorexia
 

Features

The motivation of the patient is similar to that of anorexia – to try and lose weight. However, these patients may lack the willpower and ability to restrict calorie intake, and thus there is an unusual dietary pattern of bingeing followed by vomiting. Some patients may also use diuretics to try and lose weight.
 
 

Refeeding Syndrome

This is a scenario that occurs when eating after a long period of fasting. It is not only seen in anorexia, but is also sometimes a problem after a long hospital admission.
  • Typically occurs 3-4 days after eating beings
  • The result of a change in metabolism, from metabolising fats to metabolising carbohydrates
  • Protein is a particular aetiological factor (e.g. in meat, milk and cheese)
  • There are severe electrolyte disturbances, typically thymine and phosphate deficiencies, and there may also be hypoglycaemia, and low potassium and glucose.
    • Lack of phosphate can lead to muscle weakness, which can result in diaphragmatic insufficiency.
  • These deficiencies occur because there is a massive cellular uptake of electrolytes and thus serum levels fall.
 

Signs

 

Treatment and prevention

  • Typically thiamine and vitamin B complex supplements are given when feeding resumes in anorexia.
  • Biochemistry should be closely monitored, and any abnormalities in potassium, magnesium and phosphate should be corrected