31st January 2024

Background

Introduction

Eating disorders, like many psychiatric disorders, are hard to define and are categorised based on subjective (i.e., patient-reported) symptoms, which vary around the world. What makes eating disorders different from other psychiatric disorders is the impact on physical health, and this is often included in diagnostic manuals. This section will focus on the ICD-11, as the adopted standard by the World Health Organisation since January 2022, which is very similar to the previous and more familiar ICD-10. Eating disorders can broadly be split into three key conditions: Anorexia Nervosa, Bulimia Nervosa, and Avoidant-Restrictive Food Intake Disorder. Also under this category are a series of miscellaneous presentations of Pica, Rumination-Regurgitation Disorder and “feeding or eating disorders not otherwise specified.” For the psychiatrist, differentiating these disorders is important as it impacts upon the psychological treatment. For the physician, what is key to identifying a disordered relationship with food and eating is that they must impact on the patient’s physical health, which could be syndromes related to nutritional deficiencies, dehydration or electrolyte imbalances. 

Epidemiology

The eating disorder charity BEAT estimates there are 725,000 people in the UK who suffer from an eating disorder (around 90% of patients are female, although the true percentage of male sufferers is likely 25% as many are undiagnosed). The most common disorder is Anorexia Nervosa, affecting around 15% of those who suffer an eating disorder. Most disorders start in childhood or adolescence and, if untreated, have a chronic course. There is a rough rule of thirds for treatment prognosis, 1/3 will make a full recovery, 1/3 will make a partial recovery, and 1/3 will not respond. All eating disorders, especially anorexia, have one of the highest mortality rates – not just from the physical health impact but also from suicide – up to 10-15%.

References

• World Health Organisation (2019). International Statistical Classification of Diseases and Related Health Problems, Chapter 6: Feeding or eating disorders (11th ed.). https://icd.who.int/
• National Institute for Health and Care Excellence (2017). Eating disorders: recognition and treatment. (NICE Guideline number 69). https://www.nice.org.uk/guidance/ng69
• Royal College of Psychiatrists (2022). MEED. Medical Emergencies in Eating Disorders. RCPsych Guideline CR 233