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  • Eating disorders - Facts about anorexia, bulimia and binge eating disorder

Fact sheet

Eating disorders - Facts about anorexia, bulimia and binge eating disorder

Bulimia, anorexia and other eating disorders are caused by both genes and the environment. More women than men are affected. Dieting and weight loss are often one of the first stages in the development of bulimia and anorexia but it is uncertain whether dieting is a risk factor.

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Bulimia, anorexia and other eating disorders are caused by both genes and the environment. More women than men are affected. Dieting and weight loss are often one of the first stages in the development of bulimia and anorexia but it is uncertain whether dieting is a risk factor.

A person with an eating disorder will be obsessed by food and have constant thoughts about food, eating, body shape and weight.

Other aspects of life are overshadowed when so much time and resources are used for food and eating-related activity. Eating disorders extend into other areas of life such as education, work and social relationships. Among people with eating disorders, body size and weight are of great importance to self-esteem.

Different types of eating disorders

It is common to distinguish between three types of eating disorders:

  • Anorexia (anorexia nervosa) is characterised by severe underweight and restriction of food intake. People with anorexia often experience an intense fear of gaining weight. Many feel that their body is large and fat, despite having a weight far below normal. It is common to both deny being underweight and the medical consequences of the condition. As with bulimia, some people with anorexia may vomit after eating.
  • Bulimia (bulimia nervosa) is characterised by repeated episodes of overeating. In a short period of time they will eat a lot more food than others would eat in the same situation. Each episode is followed by actions to compensate for the large food intake and to avoid weight gain. The most common behaviour is to induce vomiting but they can also abuse laxatives, fast for periods or take part in excessive amounts of exercise. People with bulimia are often normal weight or overweight, so bulimia can be more difficult for others to recognise than anorexia. About 30 per cent of people with bulimia have a history of anorexia.
  • Binge eating disorder (BED) is characterised by episodes of overeating without the corresponding compensatory action present with bulimia. Binge eating episodes are characterised by loss of control when eating. They cannot stop until they have eaten far more than others would eat in the same situation. They may eat faster than usual, even when not hungry, or eat alone because of embarrassment. Often, they will not stop until they are uncomfortably full. Episodes are often followed by shame, abhorrence or depressive thoughts. Some people with overeating disorder are overweight.

Other eating disorders

Some variants of eating disorders do not quite fit into the categories above. It is possible to satisfy some of the criteria for a medical diagnosis without satisfying all, or there may be a mix of symptoms. These are usually called unspecified or atypical eating disorders.

In addition, some people have milder problems related to body shape and eating. Population studies show that about 10 per cent have milder eating disorders. For some, eating problems may be the start of an eating disorder, while in others, they may pass without progressing to an eating disorder.


Eating disorders usually arise during adolescence. This applies especially to anorexia and bulimia, while binge eating disorders often begin in adulthood.

Based on solid national and international studies, the incidence of eating disorders in Norway for women in the age group 15-44 is estimated to be:

  • Anorexia: 0.3 per cent
  • Bulimia: 2 per cent
  • Binge eating disorder: 3 per cent

This means that 50,000 Norwegian women in the age group 15-44 will have an eating disorder at any one time. Of these, 2,700 women will have anorexia, 18,000 bulimia and 28,000 binge eating disorders (Rosenvinge JH, Götestam K, 2002).

Estimates indicate that the prevalence of anorexia has been relatively stable over the past 25 years whereas the prevalence of bulimia may have increased slightly.

Mostly affects women

Anorexia and bulimia are approximately ten times more frequent among women than men. However, for binge eating disorders there is less of a gender difference.  Many men are probably suffering from an eating disorder without having been diagnosed. There is an increasing awareness of eating disorders in men.

Serious consequences for health

Eating disorders increase the risk of a number of health problems. Complications vary depending on diagnosis and symptoms.

Anorexia leads to malnutrition that affects several organs in the body. Common complications include low body temperature, poor blood circulation, dry skin, increased facial and body hair growth, lack of menstruation and the development of osteoporosis. The condition can also cause severe cardiac arrhythmias, heart failure and changes in the central nervous system (Norwegian Board of Health, 2000).

Self-induced vomiting can disturb the body’s electrolyte and salt balance and stomach acid can erode teeth. Laxative use can interfere with intestinal function.

Compared with other psychiatric disorders, anorexia is the disease with the highest mortality rate; the risk is four to ten times higher than in the general population (Norwegian Board of Health, 2000). 

Often have additional mental health problems

Among people with eating disorders, there is a higher prevalence of mental illness than in the general population. With anorexia there is an increased incidence of depression and anxiety (including general anxiety, symptoms of compulsive disorder and social anxiety). Anxiety symptoms may be present before the eating disorder, and in some cases symptoms of depression and anxiety may continue after recovery.

For bulimia and binge eating disorders, we see an increased incidence of anxiety, depression, substance abuse and personality disorders (Klump 2008). 

Both genes and environment are important

Today, there is increased understanding that eating disorders have complex causes. Instead of studying isolated risk factors, researchers have become more concerned with studying mechanisms and vulnerability models. In these models, eating disorders are seen as a result of the interaction between genetic and environmental factors. Research from recent years suggests that there is a genetic disposition for all eating disorders. The interaction between genetic factors and the environment may determine whether one experiences an eating disorder, other mental disorders or both.

It is common to distinguish between factors that predispose, trigger and maintain an eating disorder, see Table 1.

Table 1. Factors that can predispose, trigger and maintain an eating disorder (Skårderud 2002)
 Predisposing factors  Triggering factors   Maintenance factors
  • Genes 
  • Personality (negative self-image, perfectionism) 
  • Family relationships 
  • Trauma and physical/sexual abuse
  • Cultural conditions, e.g. pressure to be thin
  • Loss and conflict 
  • Bullying, especially comments about weight and appearance when growing up 
  • Overweight as a child 
  • Early puberty 
  • High performance pressure
  • Changes in living conditions, e.g. relocation 
  • Dieting
  • Family conflicts triggered by the eating disorder
  • Negative environmental reactions
  • Psychological symptoms resulting from malnutrition and being underweight
  • Symptoms perceived as useful e.g. felling of being in control, less inner unrest and avoiding negative feelings.


Timely diagnosis and treatment are important for positive results. However, several studies show that patients with eating disorders may wait for a long time before seeking help, often more than 5 years. Many can have an ambivalent attitude to seeking help and treatment.

Several hospitals have established their own team of professionals to treat eating disorders, offering both admission and outpatient treatment. Many general practitioners also treat mild eating disorders.

Treatment results are good, with 65-85 per cent improving or recovering over time. However, there is a smaller group that has a longer recovery path.

Do you have questions about eating disorders? Contact your general practitioner for treatment or further referral.


Studies from the 1970s and 1980s show that anorexia was a rare condition in non-western countries. However, recent studies show that eating disorders, especially bulimia and overeating disorders, also occur in traditional cultures and developing countries. 

Research at the Norwegian Institute of Public Health

There are several research projects about eating disorders at the Norwegian Institute of Public Health. These are related to Twin Studies and the Norwegian Mother and Child Cohort Study (MoBa). Their aim is to map the genetic and environmental risk factors for eating disorders. Through the anorexia nervosa project "Patient Experience", it has been investigated how women with severe anorexia experience are living with and being treated for the disease.


Articles with research findings from the Norwegian Institute of Public Health:

  1. Bulik CM, Reichborn-Kjennerud T. Medical Morbidity in Binge-Eating Disoprder. Int J Eating Disorders 2003, 34:S39-S46
  2. Reichborn-Kjennerud T et al: Gender differences in binge-eating: a population-based twin study. Acta Psychiatr Scand. 2003 Sep;108(3):196-202.
  3. Reichborn-Kjennerud T et al: Genetic and Environmental Influences on Binge-Eating in the Absence of Compensatory behaviours: A Population-Based Twin Study. Int J Eat Disord Int J Eatin Disord 2004: 36;1-8.
  4. Reichborn-Kjennerud T. Undue influence of weight on self-evaluation: A population-based twin study of gender differences. Int J Eatin Disord 2004: 35; 123-132.

Other references

  • Becker AE et al: Eating behaviours and attitudes following prolonged exposure to television among ethnic Fijian adolescent girls. Br J Psych 2002:180;509-514.
  • Borresen R, Rosenvinge JH: Body dissatisfaction and dieting in 4,952 Norwegian children aged 11-15 years: less evidence for gender and age differences. Eat Weight Disord. 2003 Sep; 8(3):238-41.
  • Hoek HW, van Hoeken D. Review of the prevalence and incidence of eating disorders. Int j Eat Disord 34:383-396, 2003.
  • Klump, Bulik, Kaye, Treasure, Tyson, 2008. ”Eating disorders are serious mental illnesses”, International Journal of Eating Disorders, in press.
  • Rosenvinge JH, Götestam K, 2002. Spiseforstyrrelser – hvordan bør behandlingen organiseres? Tidsskrift for Norsk Legeforening, 122:285-288.
  • Rø Ø et al: Behandling av bulimia nervosa – resultater fra Modum Bads nervesanatorium Tidsskr Nor Lægeforen 2002; 122:260-5.
  • Skårderud F, Rosenvinge JH, og Götestam KG, 2002. Spiseforstyrrelser: en oversikt. Tidsskrift for Norsk Legeforening, 124, 1938-1942.
  • Norwegian Board of Health, 2000. Alvorlige spiseforstyrrelser: retningslinjer for behandling i spesialisthelsetjenesten. Statens helsetilsyns utredningsserie; 2000:7. IK-2714.
  • Sundgot-Borgen J et al:The effect of exercise, cognitive therapy, and nutritional counselling in treating bulimia nervosa. Med Sci Sports Exerc. 2002 Feb;34(2):190-5.
  • Wade TD et al: Sex Influences on shared Risk Factors for bulimia nervosa and other psychiatric orders. Arch Gen Psych 2004;61:251-256.