Anorexia nervosa doesn’t have a single cause. It develops from a combination of genetic vulnerability, brain chemistry differences, personality traits, life experiences, and environmental pressures that interact in ways researchers are still working to untangle. The lifetime prevalence in U.S. adults is about 0.6%, with a median age of onset around 18. Women are three times more likely to develop the condition than men, though it affects people of all genders.
Brain Chemistry and Reward Processing
Two brain signaling systems play central roles in anorexia: the dopamine pathway involved in reward and motivation, and the serotonin system that shapes mood, memory, and impulse control.
In people with anorexia, the dopamine-driven reward system appears to work differently. One leading theory holds that dieting and excessive exercise trigger a stress response, raising cortisol levels, which in turn boost dopamine. This means the behaviors that maintain the disorder (restricting food, over-exercising) may generate a neurochemical reward, reinforcing a cycle that becomes increasingly difficult to break. Brain imaging studies confirm that dopamine neurons are more active in people with anorexia, though researchers are still sorting out whether this is a pre-existing trait or a consequence of prolonged malnutrition.
Serotonin disturbances add another layer. Altered serotonin activity appears to strengthen the storage and recall of negative memories, including negative memories about one’s own body, while making it harder to override or update those memories. In practical terms, a person with these serotonin changes may find it nearly impossible to “unsee” a distorted image of their body, even when presented with objective evidence that they are underweight.
Hormones That Regulate Hunger
The body uses a sophisticated signaling system to control appetite, and two hormones sit at its center. Leptin acts as a long-term hunger suppressant. It tells the brain you have enough energy stored and reduces the rewarding feeling of eating by dialing down dopamine activity in the brain’s pleasure circuits. Ghrelin works in the opposite direction: it’s released when you haven’t eaten recently and ramps up hunger signals.
In anorexia, prolonged restriction throws this system out of balance. As body fat drops, leptin levels fall, which should theoretically increase appetite. But the brain’s response to these signals becomes blunted over time, and the normal feedback loop that drives a starving person to seek food stops functioning properly. Ghrelin levels rise in response to food deprivation, yet people with anorexia often report little or no increase in appetite. This disconnect between the body’s hunger signals and the brain’s interpretation of them helps explain why simply telling someone with anorexia to “just eat” misses the biological reality of the condition.
Perfectionism and Personality
Certain personality traits consistently show up before anorexia develops, not just alongside it. Perfectionism is the most studied. A large meta-analysis found a moderate but reliable link between perfectionism and eating disorder symptoms, with the association being even stronger in people who already have a clinical diagnosis.
Two flavors of perfectionism matter here. The first is perfectionistic strivings: setting extremely high standards for yourself. The second, which carries a stronger association with eating disorders, is perfectionistic concerns: a deep fear of making mistakes or being judged negatively. In someone vulnerable to anorexia, this fear of failure commonly shows up as an intense fear of gaining weight or eating “too much.” The person’s sense of self-worth becomes tied to their ability to control their body, and any perceived lapse feels catastrophic.
Anxiety and depression frequently co-occur with anorexia, and it can be difficult to separate cause from effect. In many cases, anxiety predates the eating disorder by years, with restriction initially serving as a way to manage overwhelming feelings. Depression often worsens as malnutrition takes hold, creating another self-reinforcing cycle.
Childhood Trauma and Adverse Experiences
Among adolescents treated for eating disorders, about 35% report at least one lifetime traumatic event. The types of trauma most closely linked to eating disorders, in order of strength, are emotional neglect, emotional abuse, physical neglect, physical abuse, and sexual abuse. The prominence of emotional neglect at the top of that list is notable because it’s often less visible than other forms of trauma.
People with anorexia who have a history of childhood abuse tend to develop the disorder earlier, experience more severe symptoms, and are more likely to engage in binge-purge behaviors rather than restriction alone. Trauma doesn’t guarantee someone will develop anorexia, but it significantly raises the risk, particularly when combined with other vulnerability factors like genetic predisposition or perfectionistic personality traits.
Social Media and Body Image
The relationship between social media and disordered eating is more nuanced than “more screen time equals more risk.” Research shows that the type of content someone consumes matters far more than how many hours they spend scrolling or how many platforms they use.
Exposure to weight loss content is specifically linked to lower body appreciation, greater fear of being judged for one’s appearance, and more frequent disordered eating behaviors. These associations hold even after accounting for gender and body size. Perhaps surprisingly, body positivity and body neutrality content doesn’t appear to have the protective effect many people assume it does.
Surveys comparing social media use over time show that people in recent years report greater body image disturbances and more frequent purging behaviors alongside significantly more time spent on image-heavy platforms like TikTok, Snapchat, and YouTube. This doesn’t prove social media causes anorexia on its own, but it clearly amplifies dissatisfaction with one’s body in people who are already vulnerable.
High-Risk Environments
Certain activities create conditions where anorexia is more likely to take root. Athletes in aesthetic sports, where appearance or leanness is judged or valued, consistently show higher rates of disordered eating and body dissatisfaction compared to athletes in other sports. Rhythmic gymnastics carries the highest documented risk, but the pattern extends across figure skating, dance, diving, and gymnastics more broadly.
The mechanism is straightforward: when your competitive success depends partly on how your body looks or how little you weigh, the external pressure to restrict food aligns with, and reinforces, any internal vulnerability that already exists. Sports that require weight categories (like wrestling or rowing) and endurance sports also carry elevated risk, though for slightly different reasons. In these settings, coaches, teammates, and scoring systems can normalize restriction in ways that delay recognition of a problem.
Genetics and Family Patterns
Anorexia runs in families, and twin studies consistently show a significant heritable component. Having a first-degree relative with anorexia raises your risk substantially. The genetic contribution isn’t a single “anorexia gene” but rather a collection of variations that influence personality (like perfectionism and anxiety), brain chemistry (dopamine and serotonin function), and metabolic traits. Some researchers have noted that alterations in estrogen signaling may affect the dopamine reward system, which could partly explain why anorexia is more common in women, particularly around puberty when estrogen levels shift dramatically.
Genetics loads the gun, but environment pulls the trigger. A person might carry every genetic vulnerability and never develop anorexia if they grow up in a supportive environment without significant body-image pressure. Conversely, someone with moderate genetic risk might develop the disorder after a combination of trauma, social pressure, and a triggering event like a diet that spirals out of control.
Two Subtypes, Different Patterns
Anorexia presents in two recognized forms. The restricting type involves weight loss through dieting, fasting, or excessive exercise without binge-purge episodes. The binge-eating/purging type involves cycles of binge eating followed by vomiting, laxative use, or other compensatory behaviors, all while maintaining a significantly low body weight. The subtype classification is based on behavior over the most recent three months, and people can shift between types over time.
The causes behind each subtype overlap but aren’t identical. Trauma history, particularly childhood abuse, is more strongly associated with the binge-purge subtype. Rigid perfectionism and high need for control are more characteristic of the restricting type. Both subtypes share the core features: restriction of food intake leading to dangerously low weight, intense fear of gaining weight, and a distorted perception of one’s own body size or shape.