Anorexia nervosa is the most lethal of all mental health conditions. People with anorexia are more than five times as likely to die as people of the same age and sex in the general population, a rate that exceeds every other eating disorder and most psychiatric diagnoses. The danger comes not from a single cause but from a cascade of damage to the heart, brain, bones, kidneys, and hormonal systems, compounded by a suicide risk 18 times higher than average.
Why the Mortality Rate Is So High
A 2024 meta-analysis in Clinical Psychology Review calculated a standardized mortality ratio of 5.21 for anorexia nervosa. That means someone with anorexia is roughly five times more likely to die during any given period than a matched peer without the disorder. For comparison, bulimia nervosa has a ratio of 2.20 and binge eating disorder sits at 1.46. The causes of death fall into two broad categories: medical complications from starvation and suicide, which is the second leading cause of death among people with eating disorders.
Heart Damage and Sudden Cardiac Death
The heart is one of the first organs affected. Prolonged malnutrition causes the heart muscle itself to shrink, a process similar to what happens to unused skeletal muscles. This reduction in heart mass lowers the amount of blood the heart can pump with each beat. Scarring of the heart tissue (myocardial fibrosis) can develop alongside this wasting, and the mitral valve may begin to prolapse as the surrounding muscle weakens.
An abnormally slow heart rate, called bradycardia, is the single most common cardiovascular finding in underweight patients. Heart rates below 60 beats per minute are typical, and rates below 40 bpm signal serious danger, particularly when paired with fainting episodes or large drops in blood pressure upon standing. These slow rhythms reflect the body’s attempt to conserve energy, but they also set the stage for more chaotic electrical patterns in the heart.
The electrical danger escalates when potassium levels drop. Potassium below 3.5 mEq/L, common in people who purge, use laxatives, or restrict fluids, stretches the interval between heartbeats in a way that can trigger a specific type of fatal arrhythmia called torsade de pointes. This is one of the main mechanisms behind sudden cardiac death in anorexia. Low phosphate levels carry a similar threat: severe depletion impairs the heart’s ability to contract and can cause fatal cardiorespiratory failure.
Brain Changes During Starvation
Brain imaging studies show that people with active anorexia have globally thinner cortical gray matter and smaller subcortical brain structures compared to healthy controls. The brain, which depends on a steady supply of glucose and fat, physically shrinks during prolonged calorie restriction. Cerebrospinal fluid fills the space left behind, visible on scans as widened gaps between brain folds.
The encouraging finding is that much of this reverses with weight restoration. Research published in Translational Psychiatry tracked brain recovery and found that cortical thickness increased markedly during the first phase of treatment, gaining about 0.08 mm as body weight climbed. Further recovery continued in the later phase. Adolescents appear to bounce back most completely, with some studies showing full normalization of gray matter after relatively brief weight restoration. Adults recover too, though small residual differences in the frontal cortex may persist even after weight is regained. These frontal regions are involved in decision-making and impulse control, which may partly explain why recovery from the behavioral aspects of anorexia can lag behind physical recovery.
Bone Loss That May Not Reverse
Up to 50% of people with anorexia develop osteoporosis. Bone density begins dropping shortly after the disorder starts, driven by low estrogen, poor nutrition, and elevated stress hormones that together suppress bone formation while accelerating bone breakdown. Unlike many other complications of anorexia, this damage can be permanent. The resulting fragile bones increase the lifetime risk of vertebral compression fractures and long bone fractures, problems that can persist decades after recovery from the eating disorder itself.
Kidney Damage and Organ Stress
The kidneys take a sustained hit from chronic dehydration, low potassium, and the repeated metabolic stress of purging or laxative abuse. These factors combine to reduce blood flow to the kidneys, causing a type of ischemic injury. Over time, the tissue develops inflammation and scarring that can progress to chronic kidney disease. Biopsy studies in anorexia patients have confirmed irreversible fibrotic changes in the kidneys, meaning that even with full nutritional recovery, some degree of kidney function may be permanently lost.
Hormonal Shutdown and Fertility
Between 68% and 89% of women with anorexia lose their menstrual periods for three or more months during the course of illness. The mechanism is straightforward: the brain’s hormonal signaling system shuts down reproductive function when it detects insufficient energy intake. Estrogen levels plummet, the uterus can regress to its prepubertal size, and the ovaries shrink until they’re sometimes undetectable on ultrasound.
What’s surprising is that long-term fertility rates in women with a history of anorexia don’t appear to differ significantly from the general population. Many women experience intermittent windows of ovulation even during active illness, and pregnancy can occur before menstruation visibly resumes, since the first released egg can be fertilized before any period signals the cycle has restarted. This means anorexia does not reliably prevent pregnancy, a misconception that can lead to unplanned pregnancies in medically vulnerable bodies.
The Danger of Refeeding
One of the more counterintuitive risks of anorexia is that the process of eating again after severe starvation is itself dangerous. When someone who has been malnourished for weeks begins taking in calories, the body shifts from burning fat to processing carbohydrates. This shift pulls phosphate, potassium, and magnesium out of the bloodstream and into cells, causing sharp drops in minerals that are already depleted. The result, known as refeeding syndrome, can cause heart arrhythmias, respiratory failure, and organ damage. For people with a body mass index at or below 14, or who have eaten almost nothing for two weeks or more, calorie reintroduction must happen very slowly under medical monitoring.
Suicide Risk
People with anorexia are 18 times more likely to die by suicide than age- and gender-matched peers. The combination of depression, anxiety, social isolation, distorted thinking patterns, and the physical effects of malnutrition on mood regulation creates what researchers have described as a “perfect storm” of suicide risk factors. This is not a minor footnote in the statistics: suicide is the second most common cause of death in eating disorders, behind only the direct medical consequences of starvation.
Long-Term Recovery Outlook
A 22-year follow-up study found that about 63% of people diagnosed with anorexia eventually reached full recovery. At the 9-year mark, only 31% had recovered, meaning that for many people the path to recovery stretches well beyond a decade. The broader literature paints a consistent picture: roughly one-third of people will improve but continue to have some symptoms, and up to one-fifth will remain chronically ill. People who have been sick for ten years or more are sometimes described as having “severe and enduring” eating disorders, though recovery is still possible even after prolonged illness.
The physical reversibility of damage depends heavily on which organ system is involved. Brain volume largely recovers with weight restoration. Heart size and function can normalize. But bone density loss and kidney scarring may be permanent, creating lasting health consequences even in people who achieve full behavioral recovery. Earlier treatment consistently produces better outcomes across every measure, which is one reason that the years between symptom onset and first treatment matter so much.