In this module we suggest that whilst you watch the video material, read the text, and if possible access the book chapter, you hold in your mind the following questions:

  • How can we diagnose and understand the so-called ‘eating disorders’—what are the different categories of such disorder?
  • How common are eating disorders, and what are the trends in prevalence and presentation?
  • What are the risks and consequences of the eating disorders?
  • What are the causes of eating disorders and how can they be distinguished from behavioural choices?
  • What can go wrong in the management of severe, life-threatening cases of anorexia nervosa?
  • How can we improve the quality of acute medical care for these patients? 

After you have digested the materials you may like to test your memory of what you have learned by answering our Multiple Choice Questions.

Patients who suffer from the so-called ‘eating disorders’ have in common the fact that they all experience preoccupations and behaviours aimed at weight loss.  Current diagnostic categories distinguish between anorexia nervosa (AN), bulimia nervosa (BN) and binge eating disorder (BED) in terms of the presence or absence of significant emaciation, and in terms of the behaviours employed to avoid weight gain.  So the hallmark of AN is significant weight loss, achieved by whatever means, whilst those in the normal or overweight range are diagnosed as suffering from BN if they use purging behaviour (such as self-induced vomiting or laxative use), but as having BED if they find themselves suffering from out-of-control ‘binges’ but do not purge.  However, even within different categories the ‘eating disorders’ are probably heterogeneous in terms of causation.

In contrast with old, unproven notions that families ‘caused’ AN, today’s clinicians commonly hold an ‘illness model’ of AN, stressing genetic and neurochemical correlates.  The weight loss of AN brings such concern that it may be all too easy to overlook the equally devastating psychological consequences of the disorder.

In patients with chronic AN , almost every organ system can be affected by malnutrition or purging behaviour.  There are endocrine changes are mostly adaptive, to optimise energy expenditure. Most are reversible with healthy nutrition over several years, but where this doesn’t occur, the brain is one of the organs that is badly affected by starvation.  This is in addition to the obsessive drive to avoid weight gain that comes to dominate every area of life 

When AN presents with consequences of starvation such as amenorrhoea, anaemia, low white count, low heart rate and low blood pressure, and sometimes deranged liver function tests and reduced thyroid activity, this should not trigger multidisciplinary searches to exclude all organic causes.  It is healthier to consider a positive diagnosis of AN, particularly in younger patients.

Patients with ‘eating’ disorders avoid anything which might cause weight gain.  They may neglect taking any medication that might result in weight gain – this can include prescribed insulin, steroids or anticonvulsants, with catastrophic results.  

Many patients also develop ‘compensatory behaviours’.  They can include purging by self-induced vomiting or taking ipecac, diuretics, laxatives, and deliberate overuse of prescribed (or acquired) drugs associated with weight loss.  It is increasingly common for patients use compulsive overactivity to reduce weight. Such patients take great pains to disguise their behaviours. The need to minutely calculate calorie balance preoccupies them at the expense of pleasurable and social activities.  

In modern times patients can use websites and social media to engage in checking behaviours, reassurance-seeking and ‘coaching’ in ways to sustain the difficult task of weight loss.  Compulsive accessing of such sites is often a part of the clinical picture, and patients become distressed when parted from their gadgets. 

It is a grave mistake either to focus unduly on either the physical aspects or on the psychological aspects of the disorder.  The psychological drives spoil lives and also interfere disastrously with treatment attempts if not robustly addressed, but failure to address physical starvation and other consequences prevents both physical and psychosocial recovery.  Different experts may specialise in their own areas, but must understand enough of each other’s field to be able to integrate care, in whichever environment is selected for treatment. It is a cliché in the speciality that AN causes ‘splitting’ of staff.  This is an easy way for the disorder to prevent effective treatment. It is therefore a crucial professional skill for clinicians to anticipate, observe and repeatedly repair such invitations to division and conflict within the multidisciplinary team.

Whilst EDs can present at any age, they most characteristically present in early-to -mid-adolescence.  The sex ratio in adults is 1:8, with more women than men afflicted. The gender distribution is less skewed in children. Outcomes differ across age groups, with higher rates of full recovery and lower mortality in adolescents than in adults (mean mortality 2% vs 5%).

In higher income countries the population lifetime prevalence of AN is about 1% in women and less than 0·5% in men.  A Scandinavian study found that rates of AN were stable across the 7-year period to 2016, with IRs ranging from 18.8 to 20.4 per 100,000 for narrowly defined AN and 33.2 to 39.5 per 100,000 for broadly defined AN, whereas overall rates of BN declined.  However, there was a significant average annual increase in AN among 10- to 14-year-old girls.Register-based studies underestimate true community prevalence of EDs. Although numbers receiving treatment have increased in recent times, only about one-third are detected by healthcare.