What are eating disorders?

Eating disorders (EDs) can be defined as “illnesses in which the people experience severe disturbances in their eating behaviours and related thoughts and emotions. People with EDs typically become pre-occupied with food and their body weight” (1).

Symptoms of EDs can involve feelings of shame and guilt towards food, undereating, overeating, binging, purging (ie. Vomiting), taking laxatives, obsessive concern over body shape and weight and changes in mood, amongst others (2).

Causes and consequences

They are all extremely serious conditions, with the highest mortality rate of among any mental illness (4). Suicide for example represents 20% of anorexia nervosa deaths (5).  

EDs are also often found in conjunction with anxiety disorders (6). Some causes involve another mental health illness, trauma, media, family history and/or societal influence (career, peers etc…) (2).

Outcomes of these conditions involve: amenorrhea, fertility problems, muscle and bone problems, neurological issues, anaemia and gastrointestinal problems (7).

Prevalence and diagnosis

The median age of onset of binge eating disorder is 21 years, with a lifetime prevalence of 2.8%, twice as high in women compared to men. 18 years was the median age of onset for both anorexia and bulimia nervosa, according to the National Institute of Mental Health, with a lifetime prevalence of 0.6% and 1.0% respectively (8).

Although these numbers may seem small, the proportion of people with an ED that are severely impaired by their condition is very high, ranging between 18.5% and 43.9%. ED-related hospital admissions have also increased by 34% in the past decade (9).

Women are affected more disproportionately by EDs, nearly twice more compared to men. Although, the National Institute of Care and Excellence estimates that up to 90% females are affected by EDs (5).

A majority of people affected by EDs will not seek out emotional or specific treatment, which makes for large underestimations as to the current prevalence of EDs, estimated at around 700000 in the UK (5).

Diagnosis of an ED is subject to specific criteria, characterized in the Diagnostic and Statistical Manual of Mental Disorders (DSM). The DSM is a document listing all mental health conditions, including EDs(10).

What is the difference between disordered eating behaviours and eating disorders?

Disordered eating can be defined as “a range of irregular eating behaviours that may or may not warrant a diagnosis of a specific eating disorder (11).”Generally, it can be agreed that disordered eating behaviours are a milder form of classic ED symptoms, with less harrowing consequences. Although they can come in the way of daily life, these can resolve without seeking professional help, which is most unlikely in the case of EDs.

What types of eating disorder are there?

The DSM-5 and the International Classification of Diseases (ICD-11) recognise officially 6 types of ED12:

  • Anorexia nervosa
  • Bulimia nervosa
  • Binge eating disorder
  • Avoidant-restrictive food intake disorder
  • Pica
  • Rumination disorder


Anorexia nervosa involves the extreme restriction of food intake, often associated with overexercising, in order to lose weight. Intense fear of weight gain or becoming ‘fat’ is common in this ED10.

Bulimia nervosa is characterised by binge episodes ie. Eating copious amounts of food in a very short period of time, and purging or using laxatives afterwards10.

Binge eating disorder is very similar to bulimia nervosa in terms of frequent binge-eating episodes, which cause significant discomfort, fullness and feelings of guilt; however, no compensatory mechanisms are associated with this ED (10).

Avoidant restrictive food intake disorder is a disorder where very little food is eaten, leading to significant weight loss and nutrient deficiencies, but where the reason for doing so is not weight loss, body shape or another medical condition, but possibly food aversions10.

Pica is an ED where non-food or non-nutritive substances (e.g. dirt, cigarette ashes) are eaten for at least one month. This ED often occurs alongside a mental disorder or medical condition, such as pregnancy (10).

Rumination disorder occurs when food is regurgitated often, and re-chewed, re-swallowed or spit out. This ED can occur is conjunction with another one of the EDs listed above (10).

A multitude of other EDs exists however, although they are not officially recognised by the DSM-5. Most of these are sub-categories of the main ones listed above and are classified under either Unspecified Feeding or Eating Disorder (UFED) or Other Specified Feeding and Eating Disorder (OSFED). Some patients meet all the criteria for one ED but will have a normal weight or Body Mass Index (BMI), or have a low frequency of episodes, relegating them to one of the unspecified categories. Some examples of these are:

  1. Night eating syndrome
  2. Diabulimia
  3. EDNOS
  4. Drunkorexia
  5. Orthorexia nervosa (10)

Orthorexia Nervosa is currently being reviewed by DSM-5 criteria to be included as an ED of its own right. It is an ED where patients are obsessed with eating healthy or ‘clean’ at all costs, otherwise intense feelings of impurity and guilt arise13.

What role does a dietitian or nutritionist play in ED management?

Treatment of an ED requires help from a complex multidisciplinary team, consisting of medical staff, therapists and pharmacists and psychotherapists, with specific inputs from dietetic and psychiatric teams. Cognitive behavioural therapy is usually offered, to tackle unhelpful thoughts around food and body image, alongside anti-depressants14.

Nutritional support is key to ED recovery. The dietetic team’s main aim is for the patient to achieve a healthy body weight and correct any deficiencies. They provide nutritional counselling to the patient, to try and establish normal eating patterns, after assessing a patient’s nutritional status, motivation and behaviours towards food.

Dietitians will look for signs of malnutrition and deficiency, calculate nutritional requirements and offer nutritional support if needed, for example in the form of oral nutritional supplements, or enteral or parenteral nutrition if the patient is unwilling to consume food through the oral route (15).

References

1)      American Psychiatric Association (2019) What are Eating Disorders? [online]. Available at: https://www.psychiatry.org/patients-families/eating-disorders/what-are-eating-disorders [Accessed April 1st, 2021].

2)      NHS (2018c) Eating Disorders [online]. Available at: https://w ww.nhs.uk/conditions/Eating-disorders/ [Accessed April 1st, 2021].

3)      Smink, F.R.E, van Hoeken, D., Hoek, H.W. (2012) Epidemiology of Eating Disorders: Incidence, Prevalence and Mortality Rates. Current Psychiatry Reports 14: pp. 406-412.

4)      National Institute of Care and Excellence (NICE) (2019) Eating disorders; how common is it? [online]. Available at: https://cks.nice.org.uk/topics/eating-disorders/background-information/prevalence/ [Accessed April 1st, 2021]

5)      Anxiety and Depression Association of America (ADAA) (2018) Eating Disorders [online]. Available at: https://adaa.org/understanding-anxiety/related-illnesses/eating-disorders [Accessed April 1st, 2021].

6)      NHS (2018a) Anorexia Nervosa [online]. Available at: https://www.nhs.uk/conditions/anorexia/ [Accessed April 1st, 2021].

7)      National Institute of Mental Health NIMH) (2017) Eating Disorders [online]. Available at: https://www.nimh.nih.gov/health/statistics/eating-disorders.shtml#:~:text=1%20The%20lifetime%20prevalence%20of%20eating%20disorders%20was,anorexia%20nervosa%2C%20bulimia%20nervosa%2C%20and%20binge%20eating%20disorder [Accessed April 1st, 2021].

8)      BEAT Eating Disorders (2021) Statistics for Journalists [online]. Available at: https://www.beateatingdisorders.org.uk/media-centre/eating-disorder-statistics [Accessed April 1st, 2021].

9)      Inside Out Institute for Eating Disorders (2021) DSM-5 Diagnostic Criteria for Eating Disorders [online]. Available at: https://insideoutinstitute.org.au/assets/dsm-5%20criteria.pdf [Accessed April 1st, 2021].

10)  Eat Right Academy of Nutrition and Dietetics (2018) What is Disordered Eating? [online]. Available at: https://www.eatright.org/health/diseases-and-conditions/eating-disorders/what-is-disordered-eating [Accessed April 1st, 2021].

11)  Treasure, J., Duarte, T.A. and Schmidt, U. (2020). Eating disorders. The Lancet, 395(10227), pp.899–911.

12)  Oberle, C.D., Samaghabadi, R.O., Hughes, E.M. (2017) Orthorexia nervosa: Assessment and correlates with gender, BMI, and personality. Appetite 108: pp. 303-310.

13)  Chawathay, K. and Ford, A. (2016) Cognitive behavioural therapy. InnovAiT 9(9): pp. 518-523.

14)  Association ADA Report. Position of the American Dietetic Association: Nutrition Intervention in the Treatment of Anorexia Nervosa, Bulimia Nervosa, and Other Eating Disorders. (2006). Journal of the American Dietetic Association, 106(12), pp.2073–2082.

Systematic review on EDs https://academic.oup.com/ajcn/article/109/5/1402/5480601

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