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A GP guide to eating disorders

GP and former psychiatrist Dr Mark Morris on how anorexia and bulimia nervosa can be tackled in a primary care setting

Key features

Anorexia nervosa

• Low body weight because of controlled eating – BMI less than 17.5kg/m2.

• Distorted body image and abnormal attitudes to food and weight.

• Amenorrhoea and, often, other signs of starvation.

• A chronic course develops in 30% of patients, with considerable morbidity and mortality.

• People with low self-esteem or who are perfectionists are more vulnerable.

• Detecting the problem early improves prognosis.

Bulimia nervosa

• Binge-eating excessive amounts of food – either genuinely excessive or perceived – with loss of self-control.

• Desire for thinness and preoccupation with food and weight.

• Strategies aimed at weight reduction – vomiting, laxative or diuretic misuse, excessive exercising.

• If there is also severe unexplained weight loss (BMI under 18kg/m2), consider a diagnosis of anorexia nervosa of the ‘binge-eating and purging' type.

Patients who suffer from anorexia or bulimia nervosa for more than 20 years stand a 20% chance of dying from their illness, either by suicide or emaciation.



• Loss of weight

• Amenorrhoea

• Other physical complications


• Low mood

• Anxiety

• Irritability

• Obsessional symptoms, particularly related to food and weight


• School or work problems

• Problems with family or relationships

• Arrests (usually for stealing) or other police contact


Remember the patient may be very ambivalent about the problem and may find it extremely difficult to talk about – a sensitive approach is important.

The assessment may have to be carried out piecemeal. The SCOFF questionnaire may help – see It has a sensitivity of 100% and specificity of 90% for anorexia nervosa. Although not diagnostic, two or more positive answers should prompt a more detailed history.

Occasionally, serious, immediate risks are present.

Management in primary care

Develop a constructive therapeutic relationship with the patient. This will help you explore the ambivalence surrounding behaviour change. Consider referral to a psychological practitioner to work on any relationship problems, perfectionism, rigid and anxious traits, sexual abuse, alcohol and/or drug abuse. Offer self-help resources.

I recommend – the eating disorder information website from the Institute of Psychiatry.

Managing anorexia nervosa

Nutrition and monitoring

• Weigh the patient regularly. The frequency of weighing and blood testing depends on the rate of progress or deterioration.

• NICE guidance recommends that in most outpatients, an average weekly weight gain of 0.5kg should be the goal. This requires about 3,500 to 7,000 extra calories a week.

• In the initial phase (three to seven days) a soft diet is recommended of about 30-40kcal/kg/day, spaced in small portions throughout the day. Oral supplements may help correct nutritional deficits.

• Vomiting and diuretic and laxative misuse can cause severe dehydration (or overhydration), acute renal failure and electrolyte imbalance. Oral fluid and electrolyte replacement may be needed.

• Beware the refeeding syndrome. When feeding begins, a sudden shift from fat to carbohydrate metabolism can lead to a marked loss of circulating phosphate within the first four days. This can result in rhabdomyolysis, leucocyte dysfunction, respiratory failure, cardiac failure, hypotension, arrhythmias, seizures, coma, and sudden death. The early clinical features of refeeding syndrome are non-specific and may go unrecognised – monitoring the physical state of the patient and blood biochemistry is very important.


In anorexia nervosa, medication does not usually help associated symptoms of anxiety or depression. These will lift as the patient's weight improves.

When to refer

• Patients with mild anorexia nervosa (BMI greater than 17kg/m2) and no significant comorbidities can be managed in primary care. But if patients don't respond within eight weeks, make a routine referral.

• Refer non-urgent patients with moderate anorexia nervosa (BMI 15-17kg/m2) and no significant comorbidities.

• Urgently refer patients with severe anorexia nervosa (BMI less than 15kg/m2), rapid weight loss or evidence of system failure to specialist services or a medical unit if their physical status is life-threatening.

In rare cases, the patient will have lost insight into the severity of the illness and will resist inpatient treatment. In these circumstances, compulsory admission to hospital will be required.

Managing bulimia nervosa

Nutrition and monitoring

Aim to get patients to eat three regular meals a day, which reduces the urge to binge. There is evidence that self-help guides that use cognitive behaviour principles can be effective.

Cognitive behaviour strategies

Using a ‘food diary', patients are encouraged to document what they eat and when. They also document what they were feeling before, during and after eating or bingeing.

They are then encouraged to look at their behaviour and think through how to make changes – such as:

• deciding on certain foods that feel ‘safe' and eating those at difficult times

• planning to do something immediately after eating to distract from vomiting

• deciding how much they are going to eat and trying to stick to that

• only keeping so much food in the house.

Patients can also use the diary to identify negative thinking that fuels negative feelings – ‘if I eat a chocolate bar, I will put on a stone' – and underlying assumptions – ‘all people who are fat are worthless'.


SSRIs can be helpful in the short term.

NICE guidance

NICE recommends most adults with bulimia nervosa have an evidence-based, self-help programme or a trial of an antidepressant as a possible first step. An alternative is 16 to 20 sessions of CBT over four to five months.

When to refer

Specialist referral is appropriate if:

• the patient doesn't make any progress

• there are serious concerns about physical or mental health

• you need to clarify the diagnosis or want advice about the best treatment

• you don't have access to evidence-based treatments, such as cognitive behaviour therapy.

Dr Mark Morris is a GP in Falmouth, Cornwall

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