Eating Disorders

Eating disorders stem from an unhealthy and distorted obsession with body image and food. There is a strong correlation with personality disorders, obsessive compulsive disorder, anxiety and other mental health disorders. Eating disorders are more common in girls. There seems to be a genetic component to the condition.


Anorexia Nervosa

In patients with anorexia nervosa, the person feel they are overweight despite evidence of normal or low body weight. It involves obsessively restricting calorie intake with the intention of losing weight. Often the person exercises excessively and may use diet pills or laxatives to restrict absorption of food.

Features of anorexia nervosa:

  • Excessive weight loss
  • Amenorrhoea
  • Lanugo hair is fine, soft hair across most of the body
  • Hypokalaemia
  • Hypotension
  • Hypothermia
  • Changes in mood, anxiety and depression
  • Solitude

Cardiac complications include arrhythmia, cardiac atrophy and sudden cardiac death.


Bulimia Nervosa

Unlike with anorexia, people with bulimia often have a normal body weight. Their body weight tends to fluctuate. The condition involves binge eating, followed by “purging” by inducing vomiting or taking laxatives to prevent the calories being absorbed.

Features of bulimia nervosa:

  • Alkalosis, due to vomiting hydrochloric acid from the stomach
  • Hypokalaemia
  • Erosion of teeth
  • Swollen salivary glands
  • Mouth ulcers
  • Gastro-oesophageal reflux and irritation
  • Calluses on the knuckles where they have been scraped across the teeth. This is called Russell’s sign.

TOM TIP: There are some unique examination findings with patients that have bulimia, which makes it a popular spot diagnosis in exams. Look out for the teenage girl with a normal body weight that presents with swelling to the face or under the jaw (salivary glands), calluses on the knuckles and alkalosis on a blood gas. The presenting complaint may be abdominal pain or reflux.


Binge Eating Disorder

Binge eating disorder is characterised by episodes where the person excessively overeats, often as an expression of underlying psychological distress. This is not a restrictive condition like anorexia or bulimia, and patients are likely to be overweight.

Binges may involve:

  • A planned binge involving “binge foods”
  • Eating very quickly
  • Unrelated to whether they are hungry or not
  • Becoming uncomfortably full
  • Eating in a “dazed state”



Patient and carer education is key to the condition. Management is centred around changing behaviour and addressing environmental factors:

  • Self help resources
  • Counselling
  • Cognitive behavioural therapy (CBT)
  • Addressing other areas of life, such as relationships and past experiences

Severe cases may require admission for observed refeeding and monitoring for refeeding syndrome.

SSRI medication may be used by a specialist in child and adolescent mental health.


Refeeding Syndrome

Refeeding syndrome occurs in people that have been in a severe nutritional deficit for an extended period, when they start to eat again. Patients are at higher risk if they have a BMI below 20 and have had little to eat for the past 5 days. The lower the BMI and the longer the period of malnutrition, the higher the risk.

Metabolism in the cells and organs dramatically slows during prolonged periods of malnutrition. As the starved cells start to process glucose, protein and fats again they use up magnesium, potassium and phosphorus. This leads to:

  • Hypomagnesaemia
  • Hypokalaemia
  • Hypophosphataemia

These patients are also at risk of cardiac arrhythmias, heart failure and fluid overload.

Management will be according to the local protocol under specialist supervision:

  • Slowly reintroducing food with restricted calories
  • Magnesium, potassium, phosphate and glucose monitoring along with other routine bloods
  • Fluid balance monitoring
  • ECG monitoring may be required in severe cases
  • Supplementation with electrolytes and vitamins, particularly B vitamins and thiamine


Last updated January 2020