Anorexia nervosa (AN) is a severe mental illness characterized by extreme food restriction, a powerful fear of weight gain, and a distorted perception of body image. The chronic state of self-imposed starvation forces the body into a survival mode, causing widespread damage across every organ system. AN has one of the highest mortality rates of any psychiatric illness. Death stems from the profound physical consequences of malnutrition and the high risk of self-harm. The mechanisms of death involve sudden cardiac events, systemic organ failure, a paradoxical risk during treatment, and suicide.
The Immediate Danger of Cardiac Complications
The most common physical cause of sudden death in Anorexia nervosa is a cardiac event, typically a fatal arrhythmia or heart failure. Chronic malnutrition and the resulting muscle wasting (cachexia) cause the heart muscle to atrophy and shrink. This reduction in heart mass compromises the organ’s ability to pump blood effectively, leading to diminished cardiac output and dangerously low blood pressure (hypotension).
The heart’s electrical stability is severely undermined by imbalances in electrolytes. Low levels of potassium (hypokalemia), magnesium, and calcium are particularly dangerous to the heart rhythm. These deficits disrupt normal electrical signaling, which can lead to a prolonged QT interval on an electrocardiogram. A long QT interval predisposes the heart to chaotic and rapid heart rhythms, such as ventricular tachyarrhythmia, causing sudden cardiac arrest. The body attempts to conserve energy by slowing functions, often resulting in bradycardia, which can also contribute to sudden collapse.
Systemic Organ Failure and Immune Compromise
Beyond the immediate threat to the heart, long-term starvation progressively degrades the body’s other major organ systems. The kidneys are highly susceptible to damage due to chronic dehydration and persistently low blood pressure. This stresses the kidneys, impairing their ability to filter waste and regulate electrolytes, which can progress to acute kidney injury or renal failure.
The liver can also be compromised by the lack of nutrients, sometimes developing malnutrition-induced hepatitis. While liver function often recovers with nutritional rehabilitation, it may rarely lead to liver failure.
The immune system becomes severely compromised, lacking the protein and energy needed to produce immune cells and antibodies. This immune suppression leaves the body unable to fight off common pathogens, significantly increasing the risk of fatal infections, such as sepsis or pneumonia.
Acute Risk During Treatment: Re-feeding Syndrome
Paradoxically, starting nutritional rehabilitation can trigger a potentially lethal complication known as re-feeding syndrome. When a severely malnourished person begins to eat, the body rapidly shifts to metabolizing carbohydrates, causing an abrupt release of insulin. This insulin spike drives essential electrolytes—notably phosphate, potassium, and magnesium—from the bloodstream into the cells to create new energy compounds. Since the body’s mineral stores were already depleted by starvation, this rapid intracellular shift causes a severe drop in serum electrolyte levels, particularly hypophosphatemia. This acute deficiency can precipitate sudden cardiac failure, respiratory distress, seizures, or coma, requiring intensive medical monitoring during initial re-feeding.
The Psychiatric Mortality Risk: Death by Suicide
A major pathway to mortality in Anorexia nervosa is suicide, which is the second leading cause of death for individuals with the disorder. The risk of death by suicide is substantially higher for individuals with AN compared to the general population, with some estimates indicating an 18-fold increased likelihood. This elevated risk is strongly linked to the high rate of co-occurring psychiatric conditions that often accompany AN.
Individuals frequently struggle with concurrent diagnoses such as major depression, generalized anxiety disorder, and obsessive-compulsive disorder. The profound psychological distress, hopelessness, and intense emotional pain associated with the chronic illness contribute significantly to suicidal thoughts and attempts. Studies suggest that many attempts occur during an active episode of major depressive disorder. The extreme nature of the disorder, along with a tendency toward impulsivity and self-harming behaviors, further amplifies the danger of a completed suicide.