About eating disorders
What are eating disorders?
An eating disorder is a complex mental illness that for some can lead to severe and permanent physical complications, and even death.1 Eating disorders are not a choice – they are serious illnesses.2
There are four main types of eating disorders – anorexia nervosa, bulimia nervosa, binge-eating disorder, and other specified feeding or eating disorders (OSFED).2
- Anorexia nervosa is characterised by the severe restriction of food intake, and generally results in significant (and dangerous) weight loss.3
- The peak age of onset of anorexia nervosa is in early to mid-adolescence but may occur at any age, including in childhood.4
- According to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition
(DSM-5) criteria, to be diagnosed with anorexia nervosa a person must display:5
- Persistent restriction of energy intake leading to significantly low body weight (within the context of the minimum expectations for their age, sex, developmental trajectory, and physical health);
- Either an intense fear of gaining weight, or of becoming fat, or persistent behaviour that interferes with weight gain (despite being significantly low in weight); and
- Disturbed perceptions of one’s body weight or shape, undue influence of body shape and weight on self-evaluation, or persistent lack of recognition of the seriousness of the current low body weight.
- Factors contributing to the development of anorexia nervosa are complex, and include a strong genetic component.6 These genes can be triggered by environmental influences, such as dieting or extreme exercise.7, 8
- Our preliminary research has shown that at a genetic level, anorexia nervosa has both psychiatric and metabolic origins6 – significant results which are helping to explain why some people can achieve, and maintain, low body mass indices, and why even after successful therapeutic renourishment, their bodies tend to revert to dangerously low weights.
- Bulimia nervosa is characterised by recurrent binge-eating episodes (consumption of unusually large amounts of food in a relatively short space of time).5, 9
- In bulimia nervosa age of onset is more commonly in later adolescence and young adulthood. 4
- According to the DSM-5 criteria, to be diagnosed with bulimia nervosa a person must display:5, 10
- Recurrent episodes of binge eating, characterised by; eating in a discreet period of time and consuming larger volumes of food than what most people would consume during a similar period of time, and under similar circumstances;
- A sense of lack of control over eating (e.g. a feeling that one cannot stop eating or control what or how much they consume);
- Recurrent inappropriate behaviours to compensate for over consumption in order to prevent weight gain, such as self-induced vomiting, misuse of laxatives, diuretics, or other medications, fasting, or excessive exercise;
- The binge eating and inappropriate compensatory behaviours occurring at least once a week for three months; and
- Self-evaluation influenced by body shape and weight.
- Binge-eating disorder involves episodes of eating unusually large amounts of food, and a loss of control.5, 11
- In binge eating disorder, similar to bulimia nervosa, the age of onset is more commonly in later adolescence and young adulthood and has a much more even gender frequency. 4
- Binge-eating episodes are associated with three (or more) of the following:5
- Eating much more rapidly than normal;
- Eating until feeling uncomfortably full;
- Eating large amounts of food when not feeling physically hungry;
- Eating alone due to embarrassment by how much one is eating; and
- Feeling disgusted with oneself, depressed, or very guilty after overeating.
Other common questions
- People experiencing some eating disorders may hold an inaccurate perception of their body size and shape, and attempt to control their weight and appearance through excessive dieting, exercising, and/or purging.12
- Personality traits of perfectionism and fear of failure, low self-esteem, and emotion avoidance are common among those living with anorexia nervosa.13 People living with anorexia nervosa often adhere to intense exercise routines.14, 15
- Accompanied by a sense of loss of control, bulimia nervosa binges are often followed by feelings of guilt and shame. Binges are often counteracted by self-induced vomiting, fasting, over-exercising and/or misuse of laxatives, enemas, or diuretics.9Eating disorders occur at any body size.16 People with bulimia nervosa may be slightly underweight, of average, or overweight status.17
- Feelings of guilt, disgust and depression often follow a binge-eating episode.5, 18 Unlike bulimia nervosa, binge-eating disorder does not involve purging. However, the illness can involve sporadic fasting and repetitive diets, as well as weight gain.19
- The lifetime prevalence of eating disorders in New Zealand is estimated to be between 1.5 and 2.1 per cent.12 Eating disorders most commonly affect those aged between 25 and 44, but can strike at any age.20 Eating disorders can affect anyone, from any gender, or cultural background.20
- Like women, men experience disturbances in body image, binge eating and maladaptive weight/shape control behaviours.21 Importantly, eating disorders among men are significantly under-diagnosed.22 Indeed, the prevalence of binge-eating disorder may be nearly as high in men as in women, and the prevalence of extreme weight control behaviours, such as extreme dietary restrictions and purging, may be increasing more rapidly in men than women.21
Some research suggests those who identify as lesbian, gay, bisexual, transgender or gender diverse may be at increased risk of developing eating disorders.23, 24
- Māori and Pacific people constitute approximately 17 per cent and eight percent of New Zealand’s population respectively.25, 26 Data suggests that eating disorders are at least as common among Māori and Pacific populations as the remainder of the population.20 Māori and Pacific populations though, are less likely to have contact with health services for mental health reasons, suggesting barriers to access.12
- For New Zealanders, the lifetime prevalence of anorexia nervosa is estimated to be 0.6 per cent, representing nearly 30,000 people.27 The prevalence of New Zealanders who have had bulimia nervosa at any stage during their lives is estimated to be 1.3 per cent – equating to more than 62,000 people.12 Almost two (1.9) per cent of New Zealand adults are expected to develop binge-eating disorder during their lifetime.19
Eating disorders cause significant distress and that impacts on the lives of the individual, their family, carers, partners and friends.28 Medical complications of eating disorders include cognitive impairment, heart complications, growth retardation and osteoporosis.4
Young people with anorexia nervosa aged between 15 and 24 years have 10 times the age-adjusted mortality rate, compared to their same-aged peers, due to medical complications and suicide.12,29, 30
Across eating disorders, psychotherapeutic interventions are the most effective and recommended first-line treatment.31
Multidisciplinary team treatment of eating disorders is the standard of care, with close coordination of medical, nutritional, and psychiatric treatments. Services range from intensive medical and psychiatric inpatient programs to residential, partial hospital, day treatment, and varying levels of outpatient care, which may entail general medical treatment, nutritional consultation and counselling, and individual, group, and family psychotherapy.31
Level of care should be determined according to a patient's overall physical status, including body mass index and medical stability, as well as psychological symptoms and social circumstances.
Hospital-level care is necessary in the context of serious medical complications or seriously impaired psychological function. It may also be necessary when there is a rapid or persistent decline in intake or weight, an inadequate response to lower levels of care, or when psychosocial or comorbidities interfere with effective outpatient management.31
There is not a standalone, distinct cause of eating disorders but rather a complex interplay among various risk factors that triggers its inception.32 Some of the factors that influence eating disorders include genetics, developmental challenges (including puberty), thinking styles (such as perfectionism), body dissatisfaction (body image has ranked among the top four concerns for young people over the past nine years33) and socio-cultural pressures.34
Twin and adoption studies highlight that genetics substantially contribute to the risk for developing eating disorders. There is a moderate-to-high heritability of anorexia nervosa, bulimia nervosa, and binge-eating disorder in females and males during adolescence and adulthood.32
Data suggests that psychological and environmental factors interact with and influence the expression of genetic risk to cause eating disorders.32
Sociocultural influences (i.e. media exposure, perceived pressures for thinness, thin-ideal internalisation, thinness expectancies) are risk factors for eating disorders, but not universally – only a subset of females and males are vulnerable to these influences.32
Personality traits have received significant attention as a contributing cause of eating disorders. Negative emotionality/neuroticism, perfectionism, and impulsivity/negative urgency personality traits have all been shown to share a causative link to eating disorders.32
- National Eating Disorders Collaboration. What is an eating disorder? . October 2019]; Available from: https://www.nedc.com.au/eating-disorders/eating-disorders-explained/something/whats-an-eating-disorder/.
- Walker, S. and C. Lloyd, Barriers and attitudes health professionals working in eating disorders experience. International Journal of Therapy and Rehabilitation, 2011. 18(7): p. 383-390.
- National Eating Disorders Collaboration. Anorexia nervosa. December 2019]; Available from: https://www.nedc.com.au/eating-disorders/eating-disorders-explained/types/anorexia-nervosa/.
- Royal Australian and New Zealand College of Psychiatrists. Clinical practice guidelines for treatment of eating disorders. 2014 October 2019]; Available from: https://www.ranzcp.org/files/resources/college_statements/clinician/cpg/eating-disorders-cpg.aspx.
- American Psychiatric Association, Diagnostic and Statistical Manual of Mental Disorders: Diagnostic and Statistical Manual of Mental Disorders. Fifth Edition ed. 2013.
- Watson, H.J., et al., Genome-wide association study identifies eight risk loci and implicates metabo-psychiatric origins for anorexia nervosa. Nature Genetics, 2019. 51(8): p. 1207-1214.
- Dittmer, N., C. Jacobi, and U. Voderholzer, Compulsive exercise in eating disorders: proposal for a definition and a clinical assessment. Journal of Eating Disorders, 2018. 6(1): p. 42.
- Himmerich, H., et al., Genetic risk factors for eating disorders: an update and insights into pathophysiology. Therapeutic Advances in Psychopharmacology, 2019. 9: p. 2045125318814734.
- Fairburn, C.G. and P.J. Harrison, Eating disorders. Lancet, 2003. 361(9355): p. 407-16.
- Eating Disorders Victoria. About the DSM-5. Jan, 2020]; Available from: https://www.eatingdisorders.org.au/eating-disorders/what-is-an-eating-disorder/classifying-eating-disorders/dsm-5.
- National Eating Disorders Collaboration. Binge eating disorder. December 2019]; Available from: https://www.nedc.com.au/eating-disorders/eating-disorders-explained/types/binge-eating-disorder/.
- Ministry of Health. Future Directions for Eating Disorders Services in New Zealand. 2008 Dec, 2019]; Available from: https://www.health.govt.nz/system/files/documents/publications/future-directions-eating-disorders-services-nz-v2.pdf.
- Bulik, C., et al., The Relation Between Eating Disorders and Components of Perfectionism. The American journal of psychiatry, 2003. 160: p. 366-8.
- Klump, K.L., et al., Academy for eating disorders position paper: eating disorders are serious mental illnesses. Int J Eat Disord, 2009. 42(2): p. 97-103.
- Kolnes, L.-J., 'Feelings stronger than reason': conflicting experiences of exercise in women with anorexia nervosa. Journal of eating disorders, 2016. 4: p. 6-6.
- National Eating Disorders Collaboration, N. Eating disorders, eating disorders explained, who is affected? . Jan, 2020 ]; Available from: https://www.nedc.com.au/eating-disorders/eating-disorders-explained/something/who-is-affected/.
- National Eating Disorders Collaboration, N. Bulimia nervosa. Jan, 2020]; Available from: https://www.nedc.com.au/eating-disorders/eating-disorders-explained/types/bulimia-nervosa/.
- Dingemans, A., U. Danner, and M. Parks, Emotion Regulation in Binge Eating Disorder: A Review. Nutrients, 2017. 9(11).
- Kessler, R.C., et al., The prevalence and correlates of binge eating disorder in the World Health Organization World Mental Health Surveys. Biol Psychiatry, 2013. 73(9): p. 904-14.
- Ministry of Health: Wellington. Te Rau Hinengaro: The New Zealand Mental Health Survey. 2006 Dec, 2019]; Available from: https://www.health.govt.nz/system/files/documents/publications/mental-health-survey.pdf.
- Mitchison, D. and J. Mond, Epidemiology of eating disorders, eating disordered behaviour, and body image disturbance in males: a narrative review. Journal of eating disorders, 2015. 3: p. 20-20.
- Strother, E., et al., Eating disorders in men: underdiagnosed, undertreated, and misunderstood. Eat Disord, 2012. 20(5): p. 346-55.
- Bell, K., E. Rieger, and J.K. Hirsch, Eating Disorder Symptoms and Proneness in Gay Men, Lesbian Women, and Transgender and Non-conforming Adults: Comparative Levels and a Proposed Mediational Model. Front Psychol, 2018. 9: p. 2692.
- Kamody, R.C., C.M. Grilo, and T. Udo, Disparities in DSM-5 defined eating disorders by sexual orientation among U.S. adults. International Journal of Eating Disorders. n/a(n/a).
- Williams, Z., K. De Bruyn, and M. Scott, The challenges of treating eating disorders in Maori. Journal of Eating Disorders, 2015. 3(Suppl 1): p. O32-O32.
- Stats NZ Tatauranga Aotearoa. 2018 Census population and dwelling counts. 2018 Jan, 2020]; Available from: https://www.stats.govt.nz/information-releases/2018-census-population-and-dwelling-counts.
- Hay, P., F. Girosi, and J. Mond, Prevalence and sociodemographic correlates of DSM-5 eating disorders in the Australian population. J Eat Disord, 2015. 3: p. 19.
- NSW GOVERNMENT Health. NSW Service Plan for People with Eating Disorders 2013-2018. DEC, 2019]; Available from: https://www.health.nsw.gov.au/mentalhealth/resources/Publications/service-plan-eating-disorders-2013-2018.pdf.
- Smink, F.R.E., D. van Hoeken, and H.W. Hoek, Epidemiology of eating disorders: incidence, prevalence and mortality rates. Current psychiatry reports, 2012. 14(4): p. 406-414.
- Fichter, M. and N. Quadflieg, Mortality in eating disorders - Results of a large prospective clinical longitudinal study. The International journal of eating disorders, 2016. 49.
- Delinsky, S.S., J.L. Derenne, and A.E. Becker, Specific Mental Health Disorders: Eating Disorders, in International Encyclopedia of Public Health (Second Edition), S.R. Quah, Editor. 2017, Academic Press: Oxford. p. 43-47.
- Culbert, K.M., S.E. Racine, and K.L. Klump, Research Review: What we have learned about the causes of eating disorders – a synthesis of sociocultural, psychological, and biological research. Journal of Child Psychology and Psychiatry, 2015. 56(11): p. 1141-1164.
- Mission Australia. Youth Survey Report. October 2019]; Available from: https://www.missionaustralia.com.au/publications/research/young-people.
- Treasure, J., et al., The experience of caregiving for severe mental illness: a comparison between anorexia nervosa and psychosis. Soc Psychiatry Psychiatr Epidemiol, 2001. 36(7): p. 343-7.