Anorexia nervosa carries one of the highest mortality rates of any psychiatric condition, roughly six times that of the general population. The damage extends far beyond weight loss, affecting nearly every organ system in the body. Here’s what prolonged malnutrition actually does.
Heart Damage and Slowed Heart Rate
The heart is a muscle, and like all muscles, it shrinks when the body is starved. This atrophy causes the heart rate to slow, a condition called bradycardia, where the resting heart rate drops below 60 beats per minute. The body is essentially conserving energy by reducing the number of heartbeats, similar to a hibernating animal. But this energy-saving mode comes with serious danger: the weakened, slower heart becomes prone to irregular rhythms that can turn fatal. Over time, the cardiovascular strain can progress to heart failure.
Electrolyte Shifts That Trigger Emergencies
Your body relies on a tight balance of minerals like potassium, sodium, and magnesium to keep the heart beating in rhythm, the muscles contracting, and the nerves firing. Starvation depletes these minerals. Low potassium is especially common and especially dangerous. When levels drop severely, it can trigger life-threatening heart rhythm abnormalities. This risk doesn’t go away when someone starts eating again. In fact, refeeding after prolonged starvation causes its own crisis: the body’s cells suddenly demand phosphorus, potassium, and magnesium to process incoming food, pulling whatever remains out of the bloodstream. This rapid shift, known as refeeding syndrome, can cause organ failure if not carefully managed.
Bone Loss That Lasts for Years
Anorexia causes significant bone thinning, and it happens faster than most people expect. Between 50% and 90% of people with anorexia develop measurable bone weakening, and 20% to 30% progress to full osteoporosis. The fracture risk increases sharply after diagnosis, particularly in the first year, and remains elevated for up to a decade. Over a 40-year period, the cumulative incidence of fractures in people diagnosed with anorexia reaches 57%.
Weight restoration can stabilize bone density, and adolescents in particular can see meaningful improvements over time. One study found that patients who maintained their weight above a certain threshold gained roughly 5% to 7% bone density at the spine and hip over 15 months. But patients who remained underweight continued losing bone even during treatment. The window for recovery is real, but it narrows the longer the illness persists.
Hormonal Disruption
Starvation suppresses the hormones that regulate reproduction, metabolism, and growth. Between 60% and 80% of people with anorexia lose their menstrual period entirely, a direct result of plummeting estrogen levels. This isn’t just a reproductive issue. Estrogen plays a key role in maintaining bone density, so its loss accelerates the skeletal damage described above. Thyroid function also drops as the body tries to conserve energy, slowing metabolism even further and contributing to fatigue, cold intolerance, and difficulty concentrating.
Brain Volume Reduction
Severe malnutrition physically shrinks the brain. Imaging studies have documented reductions in gray matter volume across multiple regions, including areas involved in movement coordination, sensory processing, and decision-making. The encouraging finding is that this reduction appears largely reversible with weight restoration, at least in younger patients who haven’t been ill for many years. For people with chronic, long-standing anorexia, the degree of recovery is less certain.
Digestive System Slowdown
When the body is denied nutrients, the entire digestive tract slows down. The stomach takes longer to empty, gut transit time increases, and the hormones that coordinate digestion become dysregulated. The practical result is a frustrating cycle: people with anorexia who try to eat often experience bloating, nausea, feeling uncomfortably full after small amounts of food, and constipation. These symptoms can reinforce the avoidance of food, making recovery harder.
Other gastrointestinal complications include heartburn, difficulty swallowing, gallstones, and in severe cases, liver injury. A rare but serious complication occurs when the main artery supplying the intestines gets compressed due to loss of the fat pad that normally cushions it, cutting off blood flow to part of the gut.
Blood Cell Abnormalities
Malnutrition impairs the bone marrow’s ability to produce blood cells. In a large study of hospitalized anorexia patients, about half had abnormally low white blood cell counts, meaning their immune systems were compromised and less able to fight infection. Roughly 16% to 20% were anemic, with too few red blood cells to efficiently carry oxygen. About 5% to 7% had low platelet counts, which affects the blood’s ability to clot. These abnormalities worsen as body weight drops. Among the most severely underweight patients (below 70% of their ideal body weight), a third had dangerously low white blood cell counts, compared to only 7% in those closer to a healthy weight.
Skin and Hair Changes
One of the more visible signs of severe anorexia is the growth of lanugo, a fine, soft, downy hair that appears on the face, arms, and torso. The body grows this hair as a form of insulation when it no longer has enough body fat to maintain warmth. Skin also becomes dry and fragile, hair on the head thins and falls out, and nails become brittle. These changes reverse with nutritional recovery, but they serve as outward markers of the serious internal damage happening simultaneously.
Mortality Risk
Anorexia is fatal more often than most people realize. The standardized mortality ratio sits between 5.9 and 6.2, meaning someone with anorexia is roughly six times more likely to die than someone of the same age and sex in the general population. Death typically results from one of two causes: organ failure from prolonged malnutrition (particularly heart failure or electrolyte-driven cardiac arrest) or suicide. The presence of other medical conditions increases the risk further. Among females with both type 1 diabetes and anorexia, for example, mortality risk climbs to more than 20 times that of the general population.