The long-term health effect most strongly associated with anorexia nervosa is bone loss, specifically osteopenia and osteoporosis. Between 50% and 90% of people with anorexia develop reduced bone mineral density, and unlike many other complications of the disorder, this damage is not fully reversible even after weight is restored. While anorexia affects nearly every organ system, bone deterioration stands out because of how common it is, how early it begins, and how persistent it remains.
Why Bone Loss Is So Common
Bones are living tissue that constantly breaks down and rebuilds. This process depends on adequate nutrition, body weight, and hormones. Anorexia disrupts all three. Estrogen deficiency, which results from the loss of menstrual periods in up to 84% of females with anorexia, was long considered the primary driver. But research now shows the picture is more complex. Hormones produced by fat tissue play an essential role in directing stem cells to become bone-building cells. When body fat drops severely, those stem cells are instead redirected toward becoming fat cells rather than bone cells, effectively starving the skeleton of new growth.
Full-blown osteoporosis develops in roughly 20% to 30% of patients with anorexia, while the milder stage of bone thinning (osteopenia) affects the majority. The consequences are concrete: decreased height, chronic pain, and a significantly increased risk of fractures both during the illness and for years afterward. For adolescents and young adults, the damage is especially concerning because the late teens and early twenties are when the body is supposed to be building peak bone mass, a reserve that protects against fractures for the rest of life. Missing that window creates a deficit that nutrition alone cannot fully close.
Other Long-Term Effects by Organ System
Heart
Anorexia causes measurable structural changes to the heart. Studies using echocardiography have found a 30% to 50% reduction in left ventricular mass in young women with the disorder, a shrinkage that is disproportionate to overall weight loss. This reduction in heart muscle can lead to mitral valve prolapse, where a heart valve doesn’t close properly because the smaller heart creates a mismatch with the valve apparatus. Fluid can also accumulate around the heart (pericardial effusion). A slow heart rate is the most common rhythm abnormality in both children and adults with anorexia. Most of these cardiac changes do improve with weight restoration, but they carry real danger during the active illness and are a major contributor to the disorder’s high mortality rate.
Brain
Brain imaging reveals one of the most visible effects of anorexia: a measurable loss of gray matter volume, with a corresponding increase in the fluid-filled spaces of the skull. The frontal lobes, which handle decision-making and impulse control, are particularly affected. Whether this damage fully reverses is still an open question. Some research shows that cortical thinning can rapidly improve with weight restoration. But other studies have found reduced blood flow in multiple brain regions that persists long after refeeding, even in people who were weight-restored, suggesting some lasting changes to brain function.
Kidneys
Kidney problems are more common than many people realize. The lifetime prevalence of kidney-related disorders, including dangerous shifts in electrolytes, is approximately 70% among people with anorexia. In severe, long-standing cases, about 5.2% of patients develop end-stage kidney disease requiring dialysis or transplant. Repeated cycles of dehydration, electrolyte imbalances, and malnutrition gradually damage the kidney’s filtering units in ways that can become irreversible.
Digestive System
Over 90% of patients with anorexia report gastrointestinal symptoms. Prolonged malnutrition weakens the muscles of the digestive tract, damages the gut lining, and reduces digestive enzyme production. Even during recovery, delayed stomach emptying causes bloating and abdominal pain after meals, and the body needs time to rebuild its capacity to process normal amounts of food.
Fertility and Pregnancy
One reassuring finding is that long-term fertility rates in women with a history of anorexia are generally similar to those of the general population. The loss of menstrual periods during active illness is typically reversible with weight gain. However, pregnancy in women with current or recent anorexia carries specific risks. Babies born to these mothers tend to have lower birth weights. Women with anorexia before pregnancy are also significantly more likely to experience severe nausea and vomiting during pregnancy: 67% of women with eating disorders reported these symptoms compared to 13% of controls in one study.
What Recovery Looks Like Physically
Weight restoration improves most physiological complications, but recovery is not instant and not uniform across organ systems. Metabolism is one example: immediately after reaching a healthy weight, people recovering from anorexia need 50 to 60 calories per kilogram of body weight per day just to maintain that weight, compared to the 30 calories per kilogram a healthy person needs. This elevated caloric requirement typically normalizes over three to six months as the body’s metabolic systems recalibrate.
Digestive discomfort during early recovery is common and expected. Fluid retention can occur, particularly in people who were using laxatives or diuretics. Acne, breast tenderness, and distressing changes in body shape are typical as weight increases. Psychologically, anxiety and depressive symptoms often intensify during weight gain before gradually easing with sustained recovery.
Bone density, however, follows a different trajectory. While some improvement occurs with weight restoration, the damage is not completely reversible. This is what makes bone loss the hallmark long-term consequence of anorexia: it persists even when everything else gets better.
Mortality Risk
Anorexia nervosa carries the highest mortality rate of any psychiatric disorder. A 2024 meta-analysis found that people with anorexia are 5.2 times more likely to die than the general population of the same age. Deaths result from cardiac complications, organ failure, and suicide. This mortality risk underscores why the physical effects of anorexia, particularly those that are irreversible like bone loss, deserve serious attention from the earliest stages of the illness.