Anorexia nervosa can damage nearly every organ system in the body, from the heart and brain to the bones and reproductive system. Some of this damage reverses with weight restoration and proper nutrition, but some does not. People with anorexia face roughly triple the mortality risk of the general population, with about 14% of deaths in this group attributed to suicide.
Heart Muscle Wasting and Dangerous Rhythms
The heart is one of the first organs affected. Up to 95% of people with anorexia develop bradycardia, a resting heart rate below 60 beats per minute. This happens for two reasons: the body dials down its metabolism to conserve energy, and the heart muscle itself begins to shrink. As calorie intake drops, the left ventricle loses mass, and the heart’s cells lose their stored energy reserves. Bradycardia in this context may actually be the body’s attempt to prevent heart failure in a weakened, atrophied heart.
Beyond a slow heart rate, anorexia causes dangerous shifts in the heart’s electrical signaling. Prolonged QT intervals, a measure of how long the heart takes to reset between beats, raise the risk of sudden cardiac arrest. These electrical abnormalities are closely tied to electrolyte imbalances, particularly low potassium and sodium levels, which disrupt the precise chemical signaling that keeps the heart beating in rhythm. The good news is that most cardiovascular changes, including heart size, function, and electrical patterns, improve with adequate refeeding. Left ventricular dysfunction, usually present without obvious symptoms, reverses in most cases after nutritional rehabilitation in a clinical setting.
Bone Loss That May Not Fully Recover
Anorexia causes severe and sometimes permanent bone damage. About 38% of people with anorexia have bone density low enough to qualify as osteoporosis, and 92% have at least some measurable bone thinning. This translates to a threefold increase in lifetime fracture risk, with up to 57% of women with anorexia breaking at least one bone during their lives.
The timing matters enormously. Women whose periods stopped before they finished puberty show a 20% larger deficit in bone density compared to those who developed amenorrhea later. Adolescent bones are supposed to be building toward their peak density during those years, and anorexia essentially halts that process. Even with treatment, bone loss continues at a significant rate. In one study, young women with anorexia lost nearly 7% of their bone density over a single year. Unlike heart complications, bone damage is one of the consequences most resistant to full reversal.
Brain Shrinkage and Cognitive Changes
The brain physically shrinks during active anorexia. Gray matter, the tissue responsible for processing information and controlling movement, decreases by about 5%. White matter, the wiring that connects brain regions, drops by roughly 2.5%. Adolescents appear to experience even larger reductions. The areas most consistently affected include regions involved in self-awareness, motor planning, and decision-making.
Interestingly, brain areas linked to eating, food cues, threat detection, and reward processing tend to be relatively spared, which may help explain why the disorder’s psychological grip persists even as other cognitive functions decline. Brain volume does improve with weight restoration, but studies tracking recovery for up to a year and a half still find lower gray matter volume compared to people who never had the disorder. Whether this gap eventually closes with longer recovery remains unclear.
Hormonal Disruption and Infertility
Anorexia suppresses the hormonal chain reaction that drives the menstrual cycle. The hypothalamus, a small region at the base of the brain, stops sending the signals that trigger ovulation. Without those signals, estrogen levels plummet to ranges comparable to postmenopause. The ovaries cannot mature or release eggs, and the uterine lining thins to the point where it no longer cycles. The result is amenorrhea, the loss of menstrual periods for three or more consecutive months, and with it, infertility.
This condition is called functional hypothalamic amenorrhea, and it strikes during what should be a woman’s peak reproductive years. Prolonged estrogen deficiency doesn’t just prevent pregnancy. It causes atrophic changes in the vaginal and urinary tract tissues, reduces vaginal lubrication, raises vaginal pH, and increases vulnerability to genitourinary infections. The uterine muscles themselves can weaken. While this form of amenorrhea is considered reversible once weight and nutrition are restored, the longer it persists, the more damage accumulates to the reproductive tract and to bone density, which depends heavily on estrogen.
Digestive System Slowdown
People with anorexia frequently experience delayed gastric emptying, meaning food sits in the stomach far longer than normal. In studies, whole-gut transit time in anorexia averaged about 67 hours compared to 38 hours in healthy controls. This creates a vicious cycle: the bloating, nausea, and early fullness caused by slow digestion make eating feel even more difficult and uncomfortable, reinforcing food avoidance.
The stomach also develops irregular contractions and episodes of electrical dysrhythmia, where the normal pacing signals that coordinate digestion become erratic. People with anorexia show roughly 20 times more dysrhythmic activity during fasting than healthy individuals. The encouraging finding is that these digestive problems are largely secondary to insufficient food intake rather than a permanent structural change. Gastric emptying improved significantly in most patients after just one month of normalized eating, and colonic transit returned to normal within about three weeks of a balanced diet. Long-term rehabilitation resolves most gastrointestinal symptoms, though some pelvic floor dysfunction may persist.
Blood Cell Production and Immune Function
Severe malnutrition disrupts the bone marrow’s ability to produce blood cells. In the most serious cases, the marrow itself undergoes atrophy or a gelatinous transformation, where normal blood-producing tissue is replaced by a jelly-like substance mixed with fat. This leads to leukopenia (low white blood cell counts), leaving the body with a weakened immune defense against infections. Anemia and other blood cell deficiencies also occur, driven both by nutrient shortages like iron and zinc and by the marrow’s impaired ability to function. The connection between bone health and blood production adds another layer: as osteoblasts (the cells that build bone) decline, they may drag down the marrow environment that supports blood cell development.
Skin, Hair, and Visible Changes
Many of anorexia’s visible signs stem from the body’s desperate attempts to conserve heat and resources. Lanugo, a layer of fine, downy hair, grows on the face, arms, and back as the body tries to insulate itself against heat loss caused by vanishing subcutaneous fat. It functions like a thin fur coat, a primitive mammalian response to cold that signals severe energy depletion.
Deficiencies in zinc, biotin, and protein make existing hair brittle and prone to falling out. Nails become fragile and ridged. Skin turns dry and flaky as the body runs low on essential fatty acids, which normally maintain the skin’s lipid barrier and prevent water loss. These changes are among the more visible warning signs and tend to improve relatively quickly once nutritional intake is restored.
What Reverses and What Doesn’t
Many of anorexia’s medical consequences improve significantly with weight restoration. Heart size, function, and electrical patterns normalize. Gastric emptying speeds up within weeks of regular eating. Hormonal cycles can restart once body weight and energy availability recover. Skin and hair changes resolve with adequate nutrition.
Bone density is the clearest example of damage that resists full reversal, particularly when anorexia begins during adolescence and disrupts peak bone-building years. Brain volume recovers substantially but may remain slightly below normal even after more than a year of recovery. Growth stunting in children and adolescents can be permanent if the disorder persists through critical developmental windows. Chronic kidney damage has been documented in cases of longstanding illness. The longer anorexia persists, the more likely its consequences shift from reversible adaptations to lasting organ damage.