Anorexia nervosa is a serious eating disorder defined by restricted food intake, an intense fear of gaining weight, and a distorted relationship with body image. It carries the highest mortality risk of any psychiatric illness, with women who have had anorexia facing roughly 2.5 times the risk of death compared to women without the condition. Though it most commonly develops during adolescence, anorexia affects people of all ages, genders, and body sizes.
Core Features of Anorexia
Three criteria define anorexia nervosa. First, a person restricts their calorie intake enough to reach a significantly low body weight for their age, sex, and developmental stage. Second, they experience an intense fear of gaining weight or consistently behave in ways that prevent weight gain. Third, their sense of self-worth becomes deeply tied to their body weight or shape, or they don’t recognize the seriousness of their low weight.
These features interact in a self-reinforcing cycle. The fear of weight gain drives restriction, restriction changes the body and brain in ways that amplify distorted thinking, and the distorted thinking makes it harder to recognize or accept the problem.
Two Subtypes
Anorexia takes two forms. The restricting type involves weight loss through severe calorie limitation, excessive exercise, or both. The binge-eating/purging type involves episodes of eating followed by self-induced vomiting or laxative misuse, sometimes alongside restriction. A person can shift between subtypes over the course of their illness.
The purging subtype carries some distinct physical signs: worn tooth enamel from repeated vomiting and calluses on the knuckles from inducing it.
What Atypical Anorexia Means
A person can meet every psychological criterion for anorexia, have lost a significant amount of weight, and still fall within a “normal” or above-normal weight range. This is classified as atypical anorexia nervosa. The name is misleading because it’s not rare at all. There is no specific weight or BMI cutoff that separates atypical anorexia from the standard diagnosis, and the medical and psychological consequences can be just as severe. Significant weight loss at any starting size can produce the same dangerous metabolic, cardiac, and hormonal effects.
Physical Effects on the Body
The physical signs of anorexia extend far beyond weight loss. As the body is deprived of adequate fuel, it begins shutting down or slowing non-essential functions to conserve energy. Heart rate drops, blood pressure falls, and irregular heart rhythms can develop. Electrolyte imbalances, particularly in sodium, potassium, and calcium, can become life-threatening because these minerals control heart function and fluid balance.
Other visible and felt changes include hair thinning or falling out, the growth of fine downy hair across the body (the body’s attempt to stay warm), dry or yellowing skin, blue-tinged fingertips, chronic fatigue, dizziness, fainting, constipation, stomach pain, swelling in the arms or legs, and an inability to tolerate cold temperatures. Anemia is common.
Bone loss is one of the most lasting consequences. Among adults with anorexia, 92% develop reduced bone density and 38% develop full osteoporosis at one or more skeletal sites. In adolescent girls, about half show measurable bone loss, and in boys the numbers are even worse, with 70% affected. Even after recovery, bone density doesn’t fully catch up. Weight restoration and the return of normal hormonal function produce about a 3% annual increase in spine density and 2% at the hip, but residual deficits persist for life. This means a person who had anorexia as a teenager may still face elevated fracture risk decades later.
Why Anorexia Develops
There is no single cause. Anorexia arises from an intersection of genetic vulnerability, brain chemistry, personality traits, and environmental pressures.
Genetics play a substantial role. Twin studies estimate that roughly 56% of the risk for developing anorexia is heritable, meaning more than half of a person’s susceptibility comes from their genes rather than their environment. Researchers have identified regions on chromosome 1 linked to restricting-type anorexia and to traits like drive for thinness and obsessional thinking.
At the brain chemistry level, two signaling systems appear especially important. Serotonin, which regulates appetite and mood, functions abnormally in people with anorexia, and these disruptions persist even after recovery, suggesting they may be a built-in vulnerability rather than just a consequence of starvation. Dopamine, which governs reward and motivation, also behaves differently. Altered dopamine activity has been linked to food aversion, hyperactivity, distorted body image, and the obsessive-compulsive patterns common in anorexia. Changes in dopamine metabolites persist after recovery as well.
Personality traits like perfectionism and rigidity are consistently found in people who develop anorexia, often predating the illness. Cultural pressure around thinness and body ideals acts as a trigger in people who are already biologically susceptible. Stressful life events, trauma, and transitions like puberty or leaving home can also set the process in motion.
Who Is Affected
Anorexia is often thought of as a condition affecting teenage girls, and incidence rates in 10- to 14-year-old girls have risen sharply over the past four decades, from 9 to 39 per 100,000 per year. But the illness appears across all demographics. In the general population, the incidence has remained relatively stable at 6 to 8 per 100,000 per year as tracked through primary care settings. Among older adults, eating disorders based on formal diagnostic criteria affect 2% to 7% of women and less than 1% of men.
Mortality and Serious Risks
Anorexia is dangerous in ways that go beyond what most people expect. Women with anorexia die at a rate of 3.24 per 1,000 person-years compared to 0.38 for women without the condition. The risk climbs with repeated hospitalizations: women with three or more admissions for anorexia face more than four times the risk of death over time.
The causes of death are varied. Suicide is a leading cause, with a nearly fivefold increase in risk. But anorexia also significantly raises the risk of dying from pneumonia (about eight times higher), diabetes and endocrine disease (more than seven times higher), liver and digestive disease, lung disease, and organ failure. The elevated risks for pneumonia and diabetes are often underappreciated by both patients and clinicians.
How Anorexia Is Treated
For adolescents, family-based treatment is considered the first-line approach when a patient is medically stable enough for outpatient care. In this model, parents take an active role in supporting their child’s eating and weight restoration, gradually handing control back as the adolescent recovers. Multiple clinical trials have established its effectiveness.
For adults, a specialized form of cognitive-behavioral therapy called CBT-E is the most well-supported option. It focuses on the thinking patterns that maintain the eating disorder, particularly how a person’s self-worth gets fused with their body shape, weight, and eating control. The approach is collaborative: the patient works with a therapist to identify and challenge these patterns, make changes to their eating, and develop self-management skills. Parents or family members may participate, but the emphasis is on the individual taking ownership of their recovery.
In both approaches, weight restoration is a critical early goal because starvation itself changes the brain in ways that worsen distorted thinking, anxiety, and rigidity. Many of the psychological symptoms of anorexia improve substantially with adequate nutrition, though the underlying vulnerabilities require ongoing therapeutic work.
Recovery Timelines and Outlook
Recovery from anorexia is possible, but it is rarely quick or linear. In a 30-year follow-up study of people diagnosed with anorexia in adolescence, 64% achieved full eating disorder symptom recovery, defined as being free of all eating disorder criteria for at least six consecutive months. The average duration of the first episode of anorexia was 3.6 years. When all episodes of eating disorders were counted together, including relapses and diagnostic shifts, the average total duration was about 10 years.
Relapse is common. Between 18 and 30 years after the initial diagnosis, one in five participants experienced an eating disorder relapse. People also frequently shift between eating disorder diagnoses over time, moving between anorexia, binge-eating disorder, and other specified eating disorders. Nearly a quarter of participants in that study never received psychiatric treatment at all, which likely affected their outcomes.
A later onset during adolescence (rather than very early onset) and lower levels of perfectionism before the illness began were both associated with better long-term outcomes. These findings point to something important: the traits and circumstances surrounding the illness matter as much as the diagnosis itself in shaping the path forward.