About eating disorders

An eating disorder is a complex mental illness that for some, can lead to debilitating and permanent physical complications, and even death.^1,2

There are three main types of eating disorders - anorexia nervosa, bulimia nervosa, and binge-eating disorder.³

Anorexia nervosa

Anorexia nervosa is characterized by severe restriction of food intake, and generally results in significant (and dangerous) weight loss.⁴
Anorexia nervosa is a serious and complex mental disorder with psychiatric and physical symptoms.³
Anorexia nervosa onset tends to peak in early-to-mid-adolescence, but may occur at any age, including during childhood.⁵
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:³
- 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 behavior 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 A genetic predisposition may be activated by environmental influences, such as dieting or extreme exercise.⁷
Personality traits of perfectionism and fear of failure, low self-esteem, and emotional avoidance are common among those living with anorexia nervosa.^8,9

Bulimia nervosa

Bulimia nervosa is characterized by recurrent binge-eating episodes (consumption of unusually large amounts of food in a relatively short period of time).³
In bulimia nervosa, age of onset is commonly in late adolescence and young adulthood.³
According to the DSM-5 criteria, to be diagnosed with bulimia nervosa, a person must display:³
- Recurrent episodes of binge eating, characterized by eating in a discreet period of time and consuming larger amounts 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 behaviors 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;
- Binge-eating and inappropriate compensatory behaviors occurring at least once a week for three months; and
- Self-evaluation influenced by body shape and weight.
Accompanied by a sense of loss of control, 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.¹⁰

Binge-eating disorder

Binge-eating disorder involves episodes of consuming unusually large amounts of food coupled with a sense of loss of control over eating.³
Similar to bulimia nervosa, the age of onset for binge-eating disorder most commonly occurs in later adolescence and young adulthood, and has a more even gender ratio than the other eating disorders.³
Binge-eating episodes are associated with three (or more) of the following:³
- 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 volume of food intake; and
- Feeling disgusted with oneself, depressed, or very guilty after over-eating.
Feelings of guilt, disgust, and depression often follow a binge-eating episode.^3,11
Unlike bulimia nervosa, binge-eating disorder does not involve regular compensatory behaviors. The illness can, however, involve sporadic fasting and occasional diets, as well as weight gain.¹²

Nearly 30 million Americans will have an eating disorder at some point during their lives.¹³
Concerningly, the prevalence of eating disorders appears to be on the rise, with the average prevalence of eating disorders having more than doubled, from 3.5 per cent to 7.8 per cent between 2000 and 2018.¹⁴
Lifetime prevalence of anorexia nervosa and related behaviors in the United States is estimated to affect 0.9% of women and 0.3% of men.¹⁵
Bulimia nervosa is estimated to affect 1.5% of women and 0.5% of men in the United States.¹⁵
As the most common eating disorder, 3.5% of women and 2% of men in the United States are estimated to have binge-eating disorder.¹⁵

Many factors influence eating disorders, including genetics, developmental transitions (including puberty, childbirth, and menopause), thinking styles (such as perfectionism), body dissatisfaction, and sociocultural pressures to be thin.¹⁸
Although social and cultural factors play a role, recent genetic research reveals a substantial genetic influence on eating disorders.¹⁹ Environment also matters as societal attitudes toward thinness can encourage behaviors that can trigger these disorders.⁹
Findings from family and twin studies indicate eating disorders are heritable.²⁰
Genetics account for 40-60 percent of the variability in eating disorders, leaving the remaining variability to be influenced by environmental factors.²⁰

References

Participate in our survey to help us better understand the genetics of eating disorders