Eating disorders develop from a collision of genetic vulnerability, psychological traits, life experiences, and environmental pressures. There is no single cause. Instead, multiple risk factors stack on top of each other, and what tips one person into an eating disorder may be completely different from what tips another. Understanding these layers helps explain why eating disorders affect people across every age, gender, and background.
Genetics Set the Stage
Eating disorders run in families, and twin studies consistently show a strong heritable component. If a close relative has anorexia, bulimia, or binge eating disorder, your own risk is significantly higher than the general population’s. But inheriting genetic risk doesn’t mean you’ll develop an eating disorder. Genes create vulnerability, and something in the environment has to switch that vulnerability on.
One of the clearest examples of this comes from research on puberty. A twin study of girls aged 10 to 15 found that among those with low estrogen levels, genetic influence on disordered eating was minimal. But among girls with high estrogen levels, those same genes became strongly active. In other words, the hormonal surge of puberty appears to “wake up” a genetic predisposition that was previously silent. This helps explain why eating disorders so often emerge during adolescence, particularly around the time of major physical changes.
Personality Traits That Increase Risk
Certain psychological traits show up again and again in people who develop eating disorders. Perfectionism is one of the most consistent. People who set rigid, impossibly high standards for themselves and feel intense distress when they fall short are more prone to channeling that drive into controlling food and body shape. Alongside perfectionism, researchers consistently find high levels of neuroticism (a tendency toward anxiety, worry, and emotional instability), obsessive-compulsiveness, and harm avoidance, which is the urge to avoid anything that might lead to punishment or disapproval.
The specific traits also differ somewhat by disorder. People with anorexia tend to score high on self-restraint and persistence and low on novelty seeking. They gravitate toward rigid control. People with bulimia, on the other hand, tend to show higher impulsivity and sensation seeking. This distinction matters because it reflects different underlying emotional patterns driving the same broad category of illness. Both groups, though, share low self-directedness and a fragile sense of identity.
It’s worth noting that these traits may also intensify once an eating disorder takes hold. Malnutrition itself can amplify rigidity, anxiety, and obsessive thinking, making it hard to separate what came first.
Childhood Trauma and Adverse Experiences
Adults with eating disorders report significantly more adverse childhood experiences (ACEs) than the general population. In one large comparison, the average ACEs score for people with eating disorders was 1.95, compared to 1.57 in a nationally representative sample. ACEs include physical, emotional, or sexual abuse, neglect, household dysfunction like parental substance use or divorce, and witnessing domestic violence.
Trauma doesn’t cause eating disorders in a straightforward way, but it creates conditions that make them more likely. Traumatic experiences can disrupt a child’s sense of safety and control, and disordered eating often functions as an attempt to regain that control or to manage overwhelming emotions. Restricting food can numb feelings. Binge eating can temporarily soothe distress. Purging can release tension. Over time, these coping strategies become entrenched.
Dieting as a Gateway
For many people, an eating disorder begins with a diet. Data from the National Eating Disorders Association shows that 35% of dieting becomes obsessive, and 20 to 25% of those obsessive diets eventually develop into full eating disorders. That progression often looks gradual: cutting out a food group, then skipping meals, then counting every calorie, then losing the ability to eat normally even when you want to.
Dieting is so common in Western cultures that it can feel like a harmless, even responsible choice. But in someone with genetic vulnerability, personality traits like perfectionism, or a history of trauma, the restriction of food intake can activate biological and psychological feedback loops that are very difficult to reverse without help. The brain responds to calorie restriction with changes in hunger hormones and reward signaling, and in susceptible individuals, those changes can lock in disordered patterns rather than prompting a return to normal eating.
An Evolutionary Clue
One provocative theory suggests that some symptoms of anorexia, specifically the ability to refuse food, deny hunger, and stay physically active while starving, may be remnants of an ancient survival mechanism. The “adapted to flee famine” hypothesis proposes that in our ancestors, losing weight below a critical threshold could trigger a set of responses designed to help nomadic groups leave an area where food had run out: suppress appetite, ignore starvation signals, and keep moving. In modern life, with no famine to flee, these archaic responses get activated without purpose and become the illness we call anorexia.
This framework helps explain something otherwise puzzling: why would a person’s brain actively fight against eating when the body is starving? If the behavior is rooted in an old adaptation rather than a conscious choice, the answer is that the brain is running a program designed for a scenario that no longer exists. Similar food-restriction and hyperactivity patterns have been observed in animals under starvation conditions, which supports the idea that this is a biological response, not simply a psychological one.
Social Media and Cultural Pressure
Cultural ideals around thinness and appearance have always played a role in eating disorders, but social media has intensified that pressure dramatically. The difference between a magazine cover and a social media feed is volume and personalization. Algorithms learn what you engage with and serve you more of it, creating a feedback loop where body-focused content crowds out everything else.
Research has found significant associations between social media use and multiple types of disordered eating, including binge eating, purging, severe restriction, and orthorexia (a fixation on “clean” or “healthy” eating that becomes pathological). The pathway is straightforward: social media exposure increases body dissatisfaction, and body dissatisfaction is one of the strongest predictors of disordered eating. Content like “what I eat in a day” videos, body-checking trends, and influencers promoting extreme diets normalizes restriction in ways that can be especially harmful to younger viewers.
One practical step that clinicians recommend is auditing the accounts you follow and unfollowing or scrolling past content that promotes comparison or makes you feel worse about your body. This won’t prevent an eating disorder on its own, but it reduces one significant source of environmental pressure.
Who Gets Eating Disorders
Eating disorders affect people of every demographic, though rates vary. Among adolescents, the lifetime prevalence is about 2.7%, with girls affected at roughly twice the rate of boys (3.8% versus 1.5%). In adults, the gap varies by diagnosis. Binge eating disorder is about twice as common in women as in men. Bulimia is five times more common in women. Anorexia is three times more common in women.
These numbers almost certainly undercount men and boys, who are less likely to be screened, less likely to recognize their symptoms as an eating disorder, and less likely to seek treatment. Male eating disorders often look different: more focused on muscularity and leanness than thinness, and more intertwined with compulsive exercise. The stereotype that eating disorders are a young, white, female illness has historically delayed diagnosis for everyone who doesn’t fit that profile, including men, people of color, older adults, and people in larger bodies.
How These Factors Combine
No single risk factor is enough on its own. A person might carry genetic vulnerability and go their entire life without developing an eating disorder if they never encounter the environmental triggers that activate it. Someone else might diet heavily without consequence because they lack the personality traits or biological predisposition that turns restriction into a clinical disorder. The question of “why do people get eating disorders” is really a question about accumulation: how many risk factors are present, how intensely they interact, and whether a triggering event, like puberty, a stressful life transition, trauma, or a first diet, sets the cascade in motion.
This is also why eating disorders are not a choice or a phase. They sit at the intersection of biology, psychology, and environment, driven by forces that are largely outside conscious control. The brain and body changes that sustain them are real, measurable, and require targeted treatment to reverse.