Causes of Eating Disorders: What Every Concerned Person Needs to Know
Eating disorders are biopsychosocial illnesses, which means that they emerge from a complex interplay of biological, psychological, and sociocultural forces. Each person who develops an eating disorder is affected to different degrees by each of these factors.
The most important biological risk factor for eating disorders is genetic inheritance. Research suggests that anorexia and bulimia in particular are highly heritable; having a parent with an eating disorder increases risk of developing one yourself. That doesn’t mean that there is a single gene that causes eating disorders, but your genes might predispose you to coping with anxiety and depression with food.
Just how heritable are eating disorders? While research findings vary, one study found that individuals are more than eleven times more likely to develop Anorexia Nervosa if one of their parents experienced the illness. Individuals who have a parent with Bulimia Nervosa are between four and ten times more likely to develop the illness than those who do not.¹
But it’s difficult to parse out just how much of this risk is due to genetic inheritance, and how much is due to the environment one grows up in. That’s why researchers also recognize a second, related pool of influences: psychological factors.
One study found that individuals are more than eleven times more likely to develop Anorexia Nervosa if one of their parents experienced the illness.
One of the biggest psychological risk factors is trauma. Trauma is any experience that overwhelms a person’s ability to cope. Trauma is defined by how a person experiences an event, not by the facts of the event itself. This is an important distinction, because it highlights the fact that trauma is subjective. Two people can experience the same event and one walk away feeling traumatized, while the other is relatively unphased. This doesn’t mean that one person is strong and other is weak. The way we process a distressing event has everything to do with the emotional resources we have developed over up to that point in our lifetime.
When individuals experience trauma, they may be more likely to use unhealthy behaviors — such as overeating or drinking alcohol — to make themselves feel better. Scientists often say that when it comes to eating disorders, “genes load the gun and trauma pulls the trigger.”
Trauma is any experience that overwhelms a person’s ability to cope.
Finally, there are many sociocultural factors that can lead to eating disorders. According to psychiatric historian Edward Shorter, society and culture provides a “symptom pool” — a set of culturally legitimate symptoms through which members of a society typically express their distress. We may unconsciously latch onto behaviors in the symptom pool (e.g. purging, drinking, or restricting) to express and cope with suffering, without even realizing we’re doing it. A refusal to eat and emaciated body may be the unconscious mind's way of saying, "I'm not okay."
This explains, in part, why eating disorders are more prevalent in western, industrialized countries² (although this is changing with globalization). Those who grow up in these societies are more exposed to messages about dieting, cosmetic fixes, and alcohol from an early age. Young people may try dieting or purging to lose weight or fit in with their friends, then find it helps them cope with emotional distress. Those who grow up in alcoholic families may internalize the idea that drinking takes the edge off or makes them more fun.
Finally, many of us develop a complicated relationship with food directly from our families of origin. Our parents might offer sweet or rich foods as a reward for good behaviors; or alternatively, we may be encouraged to restrict our food to maintain a desirable figure. For those with a genetic predisposition to eating disorders or a history of trauma, these messages can be the trigger for behaviors that later become full blown eating disorders.
A refusal to eat and emaciated body may be the unconscious mind's way of saying, "I'm not okay."
References1   Thornton LM, Mazzeo SE, Bulik CM. The Heritability of Eating Disorders: Methods and Current Findings. Current topics in behavioral neurosciences. 2011;6:141-156.
2   Makino, Maria, Koji Tsuboi, and Lorraine Dennerstein. "Prevalence of eating disorders: a comparison of Western and non-Western countries." Medscape General Medicine 6.3 (2004).