The Different Causes of Eating Disorders

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When a person gets sick, it's natural to want to understand why. With eating disorders, which are associated with many myths and negative stereotypes, the question of causation can be especially confusing.

The culture at large commonly blames eating disorders on oversimplified explanations, such as the media’s promotion of unrealistically slender models or on bad parenting. Even some health professionals buy into these explanations.

But research shows that families—longtime scapegoats—do not cause eating disorders, at least not in any simple, straightforward manner.

While growing up in a dysfunctional home could increase the risk for a number of psychological problems, including eating disorders, it does not condemn a child to an eating disorder or any other psychological disorder.

Scientists can’t say for sure what exactly causes an eating disorder or predict who will develop an eating disorder. In general, most experts agree that eating disorders are complicated illnesses that stem not from a single cause but from a complex interaction of biological, psychological, and environmental factors. There are many different pathways to the development of an eating disorder from binge eating disorder to anorexia nervosa to bulimia nervosa.

Risk Factors for Eating Disorders

Many factors have been, or are being, studied as possible contributors to the development of eating disorders. Across all types of eating disorders, it is likely that mental health and body image-related factors play a significant role in causing eating disorders.

Mental Health

Mental health risk factors can include anxiety, depression, low self-esteem, and trauma such as childhood sexual abuse. Social stressors, such as peer pressure and bullying, may also be involved.

Body Image

Risk factors related to eating behaviors and body image may also be tied to the development of eating disorders. These could include weight-related teasing and critical comments about weight; having a fixation with a thin body; early childhood feeding, eating, or gastrointestinal problems; and body dissatisfaction.

Risk Factors for Specific Eating Disorders

Risk factor research focuses on identifying traits or experiences that precede the development of a specific disorder (not just the overall category of eating disorders). For a risk factor to be shown as a causal factor, the risk factor must be shown to come before the development of the eating disorder. It also must be capable of being manipulated to prevent the occurrence of the disorder. For example, smoking is a causal risk factor for lung cancer; it comes before the development of the disease, and not smoking reduces one’s risk of developing lung cancer.

Because eating disorders are relatively rare and diverse disorders, it is difficult and expensive to perform the kinds of large and long-term studies needed to better assess risk factors. To date, there is limited risk factor research that has successfully demonstrated causality, but a 2015 research study found these causal risk factors for eating disorders.

Anorexia Nervosa

People with anorexia nervosa restrict their food intake, have an intense fear of weight gain, and have a distorted perception of their weight and health. Having a low body mass index (BMI)—essentially, being underweight—has been identified as a risk factor. However, anorexia nervosa can still happen in people with a BMI in the normal range.

Bulimia Nervosa

Bulimia nervosa, characterized by repeated episodes of binge eating and purging, has several identified risk factors. These include believing that thinness is equivalent to attractiveness (thin-ideal internalization), having a negative body image (body dissatisfaction), perceiving pressure to be thin, having a negative effect, and dieting.

Binge Eating Disorder

Binge eating disorder is similar to bulimia nervosa but without the purging aspect. This eating disorder was added to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) in 2013. The 2015 study did not identify any causal risk factors for BED, but a 2017 study suggests that negative urgency (a "tendency to act impulsively when distressed") is involved. A study published in 2016 noted that in girls, depressive symptoms, low self-esteem, and body dissatisfaction in adolescence was associated with binge eating in adulthood.

Purging Disorder

Purging disorder is also similar to bulimia nervosa, but in this case, the behavior is limited to purging without binge eating. The only causal risk factor identified by the 2015 research is dieting. Other research has suggested that risk factors for purging disorder are similar to those for bulimia nervosa and binge eating.

Identifying actual causal factors for a specific eating disorder is complicated. Determining whether these factors are present in an individual can be difficult. Also, the presence of these factors predicts higher risk but does not guarantee the development of an eating disorder.

Genetic Factors

Coming from a family with a history of eating disorders can increase a person's risk of developing an eating disorder. A portion of this increased risk could be due to the modeling of eating disorder-linked behaviors within a family (e.g., observing a family member dieting). However, twin study research, which can isolate the role of genetics, has confirmed that approximately 40% to 60% of the risk for anorexia nervosa, bulimia nervosa, and binge eating disorder arises from genetic influence.

The largest and most rigorous genetic investigation of eating disorders ever conducted, the Anorexia Nervosa Genetics Initiative (ANGI), is currently underway in the United States, Sweden, Australia, United Kingdom, and Denmark. This research could provide more information about the genetic profile that contributes to eating disorders.

These findings do not imply that there is a single eating disorder gene, or even that genes cause eating disorders. Some individuals may inherit traits such as anxiety, fear, perfectionism, or moodiness that have been associated with the development of an eating disorder. These aspects of temperament have also been linked to a number of other disorders.

For some people, variations in several different genes contribute to traits that, in turn, increase or decrease their risk for eating disorders.

Prevalence in Families

Some people with eating disorders are able to identify several other family members who also had eating disorders. There are certain families in which the risk of eating disorders is much higher than in the general population, but such families are relatively rare. Even a high-risk family history indicating an increased genetic risk does not mean that a person is destined to develop an eating disorder.

Conversely, not everyone who has an eating disorder can identify another family member with one. A clear majority of eating disorder cases are sporadic, with no family history. Given the smaller size of today’s families, there is often not enough data to determine whether a specific individual has a genetic tendency. In addition, eating disorders are stigmatized diseases, and family members often do not share their struggles with their disorder.

Environmental Factors

Much of the earlier research on eating disorders examined environmental risk factors. As a result, they are frequently blamed for causing eating disorders. Environmental factors include events and influences in an individual’s life, such as diet culture, the media, trauma, and weight teasing. Influences such as gender, ethnicity, or certain athletic settings can strengthen or lessen other environmental factors.

One model for understanding some of the socio-cultural risk factors for eating disorders is the tripartite model. It proposes that exposure to media, peer, and parental messages all contribute to whether a person idealizes thinness and engages in social comparison. These two factors (idealization and social comparison) may potentially lead to poor body image and various forms of disordered eating.

Society and culture do influence eating behavior as well as our concept of ideal body shape. However, such environmental factors cannot fully account for the presence of eating disorders. If they did, 100% of the people exposed to the environmental factor(s) would develop an eating disorder, which we know is not the case.

Protective Environmental Factors

Some environmental factors could help protect people from developing eating disorders. These could include family meals, eating breakfast, emotional regulation skills, and mindfulness techniques.

Techniques that help groups and individuals question and challenge unrealistic ideals of beauty (including the glorification of thinness and the stigmatization of overweight people) are also helpful and protective. Many of these environmental changes, such as improving the status and power of women, reducing the objectification of both men and women, and increasing respect for people of all sizes and shapes, will benefit everyone, not just those at risk for eating disorders. These changes help create kinder and safer—and likely more protective—communities.

Gene and Environment Interplay

Neither genes (nature) nor environment (nurture) cause eating disorders on their own. Eating disorders are likely the result of a complicated interplay of these factors. Even when a precipitating factor (such as a traumatic event) can be identified, there is almost always a combination of other contributing factors. The precipitating factor is most likely the trigger that tripped a cascade of events.

Genetic susceptibility may influence their response to certain stressors. For example:

  • A person who is genetically susceptible to an eating disorder may be more sensitive to weight-related teasing and have a heightened reaction to it (for instance, initiating a diet that snowballs into a disorder).
  • A person who is genetically vulnerable may continue dieting much longer than peers who diet and then stop.
  • A person who has the temperament that commonly underlies anorexia nervosa (anxious and perfectionistic) may seek out the types of social environments that contribute to the onset of dieting.

Epigenetics

The emerging field of epigenetics, the study of whether, how, and when genes are expressed, offers further insight. Epigenetics explains that certain environmental factors determine the expression of genes or even turn certain genes on or off in the next generation. Thus, stress to a parent alters not only their behavior but can actually turn genes on and off in offspring who were not even exposed to that stressor.

In terms of eating disorders, there is evidence that the longer a person has anorexia nervosa, the greater the chance they will have alterations in how their genes are expressed. It appears that malnourishment could turn on or off certain genes, which influence the course of the disorder. However, epigenetic studies of eating disorders are in their infancy.

A Word From Verywell

Just as environmental factors can increase a person's susceptibility to an eating disorder, the converse is also true: Changing the environment can facilitate prevention and recovery. For example, growing up with warm, nurturing parents could mitigate genes that predispose someone to anxiety.

However, chance and luck also play a role, and individuals vary in their genetic risk. Even in the face of every preventative measure, some people with extremely high genetic risks may still go on to develop an eating disorder after just one or two triggering events that are outside of their control. Others who have low genetic risk may show resilience to developing an eating disorder even in the face of many potential environmental risk factors.

When someone develops an eating disorder, it’s no one’s fault. The cause of eating disorders is too complex to attribute blame to any one person, event, or gene.

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