Anorexia nervosa

Contributed by Dr Jane Morris, consultant psychiatrist, Royal Edinburgh Hospital, Edinburgh.

Section 1: Epidemiology
Anorexia nervosa is a syndrome of obsessional weight loss and extreme fear of weight gain. It has existed for centuries, even in the absence of cultural preference for leanness.

Patients with anorexia share the drive for thinness with patients with normal weight bulimia nervosa, but those who maintain low weight for long periods may be genetically different from those who binge and purge.

Some 90 per cent of patients are female but males also develop anorexia. Although all ages are affected, the average age of onset is 15 years.

Anorexia is difficult to manage (photograph: istock)

Anorexia is the most common cause of pathological weight loss in young women and the most common cause of admission to child and adolescent psychiatric wards.

The average GP list includes two or three patients with serious anorexia, and there will be many more in student health centres.

Four per cent of women develop a significant eating disorder during their life, but only a minority are low weight anorexia. It is the most lethal of psychiatric conditions and one of the hardest to manage successfully.

Family studies, twin studies and genetic analyses demonstrate high heritability.1

Anorexia nervosa is often associated with personal and family obsessive-compulsive symptoms with perceptual and cognitive inflexibility, independent of the starved state.

Genetic research is exploring abnormalities of serotonergic function, which may be trait markers for eating disorders.

Psychiatric classifications such as ICD10 and DSM-IV (see box) define anorexia nervosa as deliberate weight loss with fear of weight gain and a problem of body image that translates all distress into a perception that the body is too fat.

To meet diagnostic criteria, at least 15 per cent of the minimum normal weight is lost. In adults, this translates as BMI below 17.5. Menstruation is absent - although the contraceptive pill still causes withdrawal bleeds.

In men, low testosterone causes atrophied genitalia and absence of morning erections.

In restrictive anorexia nervosa, low weight is achieved by starvation alone, or with overactivity.

The binge-purge subtype involves vomiting, laxatives, diuretics or slimming pills to get rid of calories.

These strict criteria exclude many who would fit into the spirit of the diagnosis. For example, a young woman with a BMI of 18 might cease menstruating if she is heavily muscled because of obsessive exercising.

On the other hand, some delicately-built Eastern women naturally menstruate and become pregnant with low BMIs.

DSM-IV Criteria for Anorexia Nervosa

A. Refusal to maintain body weight at or above a minimally normal weight for age and height (eg weight loss leading to maintenance of body weight less than 85% of that expected or failure to make expected weight gain during period of growth, leading to body weight less than 85% of expected).

B. Intense fear of gaining weight or becoming fat, even though underweight.

C. Disturbance in the way in which one's body weight or shape is experienced, undue influence of body weight or shape on self-evaluation, or denial of the seriousness of the current low body weight.

D. In post-menarchal females, amenorrhoea, i.e. the absence of at least three consecutive menstrual cycles.

Section 2: Diagnosis
Patients may be defensive about their practices, so it is helpful to hear also from an informant such as a friend or parent.

Ask about the timescale of weight loss, the patient's highest and lowest weights, preferred weight and menstruation. Get an idea of current daily food intake, alcohol, drugs and medication.

Anorexia involves a whole range of weight-losing behaviours. Remember to ask about vomiting, compulsive overactivity, laxatives, diet pills, herbal medicines and exposure to cold.

These interfere with health and social function as well as impeding weight gain.

Physical assessment
Physical sequelae of starvation are no less dangerous for being secondary to the core psychopathology.

It is essential to measure and weigh patients. BMI distinguishes anorexia from other eating disorders and provides a baseline for monitoring trends.

A BMI below 14, or precipitous weight loss (>1kg/week), is dangerous. Mortality is increased by purging or substance abuse. Such patients should be urgently discussed with specialists.

Some need hospital admission, using detention under the Mental Health Act if necessary to save life.

Particular danger signs in emaciated patients are weakness, such as when climbing stairs, rising from a squat, chest pain and cognitive slowing. ECGs help monitor cardiac status.

Where there is no immediate danger, blood tests demonstrate that your concern extends beyond the number on the scales. Glucose levels are generally low in patients with anorexia nervosa.

The thyroid is often protectively underactive. U&Es may show low urea (reflecting protein intake) and low potassium (vomiting).

Liver function abnormalities may reveal substance abuse, although extreme starvation alone causes liver damage.

Anorexia often causes anaemia. If white cell count is elevated, consider infection. Neutropenia is usual, but consult microbiologists if significantly below 1x109/L.

Annual DEXA bone scans monitor the risk of osteoporosis. Remember pregnancy tests and contraceptive advice: some women become pregnant at unhealthily low weight, and vomiting makes oral contraception unreliable. Always assess mood, both to find common ground with patients who reject physical concerns and because suicide risk is raised in anorexia.

In our concern not to overlook endocrine, GI and other causes of weight loss, patients are often over-investigated before anorexia is diagnosed.

We can routinely ask patients about eating and exercise. Menstrual irregularities, fertility problems, unexplained 'funny turns' and chronic fatigue should alert us to possible anorexia.

Some GI complaints are both the consequence of and the 'cover' for eating disorders. Psychological presentations include depression, anxiety, obsessionality and interpersonal problems.

While females are at higher risk, male patients with unexplained weight loss should be asked about diet and exercise.

The SCOFF questionnaire is a validated brief screen for eating disorders (see box).

Two or more positive answers should prompt further assessment, using both clinical interview and possibly the Eating Disorders Diagnostic Interview, self-report Questionnaire (EDE-Q).2

SCOFF questionnaire3

  • Do you make yourself sick because you feel uncomfortably full?
  • Do you worry you have lost control over how much you eat?
  • Have you recently lost more than one stone (6kg) in weight over a three month period?
  • Do you believe yourself to be fat when others say you are thin?
  • Would you say that food dominates your life?

Section 3: Management
Treatment may take from six months to six years or more, although specialist treatment is likely to be episodic rather than continuous.

GPs can forge and maintain a therapeutic relationship. To patients, eating disorders can feel like solutions to difficulties. Even when patients realise their 'solution' causes problems, they remain ambivalent.

Patients find recovery less daunting if they can learn alternative coping skills, but attempts to frighten them into eating only increase their habitual anxiety-reducing strategy, weight loss.

Current treatments
Admission for rest, warmth and medical monitoring can be lifesaving, particularly in winter when most deaths occur.

A specialist unit, or child and adolescent ward, is the ideal environment.

Recovery cannot occur without renutrition, but specialist dietetic input is neither necessary nor sufficient for outpatients. The problem is less a matter of knowing what to eat, more a case of how to tolerate resulting weight gain.

Recovery occurs only when the patient is persuaded to voluntarily maintain a healthy weight. Supportive therapy is needed to support non-negotiable life-saving feeding, while motivational approaches and focused psychotherapies take over in outpatient clinics as health improves.

Family support - not necessarily traditional conjoint family therapy - is the most effective treatment so far demonstrated for anorexia nervosa, particularly for patients living at home.

Since extreme weight loss may become a 'defence' against all forms of distress, it is important to address co-morbid conditions such as depression and anxiety.

Patient drawings may reveal their views, such as anorexia as shelter

However, a malnourished brain simply cannot produce the substrates for neurochemicals essential in mediating euthymia, serenity and confidence.

SSRIs, in higher than normal dosages (such as fluoxetine at doses of 40-60mg rather than the usual 20mg), may show benefit, but it is always important to avoid drugs that may prolong the QTc interval and threaten the weakened heart such as 'old' antipsychotics, tricyclic antidepressants, some antihistamines and macrolide antibiotics.

New developments
The finding that neither medication nor psychotherapies have much to offer low weight anorexics has been challenged.

Fairburn's refinement of cognitive therapy 'CBT-E' offers 'pick and mix' modules for the treatment of eating disorders including anorexia nervosa, if BMIs is above 15.2

'Cognitive remediation therapy' is a novel approach based on the findings that many anorexic patients show reduced central coherence on neurocognitive testing. Specific puzzles help patients become better able to see the bigger picture.4

Most recently, trials in the US have shown that the anti-psychotic drug olanzapine may significantly improve outcomes in anorexia.5

The NICE guideline on eating disorders is particularly useful.6

Section 4: Prognosis
Sten Theander's early follow-up studies found that a shocking 20 per cent of anorexic patients died of causes related to the disorder.7 Even now, mortality in anorexia is 10 times that in the general population and is among the top three or four causes of death in teenagers.

Today's lower mortality figures partly reflect changes in diagnostic criteria - 15 per cent body weight to be lost before making the diagnosis (BMI <17.5) compared with 25 per cent (BMI <15).

Improved management may also contribute to more favourable longevity; it is now acknowledged that a tolerant, respectful relationship allows long-term physical monitoring and support to be offered.8

Around one-third of patients do not fully recover but are at least enabled to live valuable or tolerable lives.

Some deaths result from ambivalently-taken overdoses that would not have killed healthy weight individuals.

Although starvation inevitably results in depression, we cannot conclude that all these 'suicides' were intended as such. Likewise, the effects of substance abuse are greatly amplified at low weight.

Hypothermia, infections (including TB) and organ failure account for many fatalities. The starved heart is especially vulnerable when over-exercised.

Follow up
When anorexia acutely threatens life we are ethically and legally obliged to take action.

More generally, medical monitoring and a listening ear are invaluable in the recovery of patients with anorexia. Recent studies show that recovery is still possible 20 years after the onset of anorexia.

Anorexia places demands on a whole range of services that are not used to co-ordinating care. Treatment involves many transitions, and these are peak times for relapse and de-compensation.

The young people and families affected tend to be highly-driven people who have much to contribute to society, and anorexia is one of the few psychiatric disorders where complete lasting recovery can occur.

  • 23-28 February is Eating Disorders Awareness week. For more information visit


1. Bulik C M, Slof-Op't Landt M C, van Furth E F, Sullivan P F. The genetics of anorexia nervosa. Annu Rev Nutr 2007; 27: 263-75.

2. Fairburn C. Cognitive Behavior Therapy and Eating Disorders. New York: Guilford Press, 2008.

3. Morgan J, Reid F, Lacey J. The SCOFF questionnaire: assessment of a new screening tool for eating disorders. BMJ 1999; 319(7,223): 1,467-8.

4. Tchanturia K, Davies H, Campbell I C. Cognitive remediation therapy for patients with anorexia nervosa. Ann Gen Psychiatry 2007; 6: 14.

5. Bissada H, Tasca GA, Barber AM, Bradwejn J. Olanzapine in the treatment of low body weight and obsessive thinking in women with anorexia nervosa. Am J Psychiatry 2008; 165(10): 1,281-8.

6. NICE (2004). Eating disorders: core interventions in the treatment and management of anorexia nervosa, bulimia nervosa and related eating disorders. Nice Clinical Guideline No 9. London: National Institute for Clinical Excellence. Available from:

7. Theander S. Outcome and prognosis in anorexia nervosa and bulimia. J Psychiatr Res 1985; 19(2-3): 493-508.

8. Lowe B, Zipfel S, Buchholz C et al. Long-term outcome of anorexia nervosa in a prospective 21-year follow-up. Psychol Med 2001; 31(5): 881-90.

Further reading

  • C Laird Birmingham, Pierre J V Beumont, eds (2004). Medical Management of Eating Disorders: A practical Handbook for Healthcare Professionals. Cambridge University Press.
  • Morris J, ed. (2008). ABC of Eating Disorders. Blackwell.
  • Treasure, Janet (1997). Breaking Free from Anorexia Nervosa: A Survival Guide for Families, Friends and Sufferers. Hove: Psychology Press.


  • - The Royal College of Psychiatrists' website has a range of useful information both for professionals and for carers and sufferers of all ages.
  • - The website of 'BEAT', formerly known as the Eating Disorders Association, offers information and help for lay people on all aspects of eating disorders.

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