Eating disorders affect nearly every organ system in the body. The damage ranges from reversible digestive discomfort to life-threatening cardiac events, and the severity depends on the type of disorder, how long it has persisted, and how early treatment begins. Anorexia nervosa carries an almost sixfold increased risk of death compared to the general population, making it one of the deadliest psychiatric conditions. Bulimia nervosa roughly doubles that risk.
Heart and Circulatory System
The heart is one of the first organs to show measurable damage from restrictive eating. In anorexia nervosa, dangerously slow heart rates are almost universal. In one study using 24-hour heart monitoring, 95% of patients showed prolonged periods where their heart rate dropped below 50 beats per minute, with some individuals recording rates as low as 26 bpm. For context, a healthy resting heart rate typically falls between 60 and 100 bpm. This slowing, called bradycardia, happens because the heart muscle weakens and shrinks as the body breaks down its own tissue for fuel.
Structural changes to the heart also develop. About 13% of anorexia patients in one study showed mitral valve prolapse, a condition where one of the heart’s valves doesn’t close properly. Others developed valve leakage or narrowing. These changes increase the risk of heart failure, which remains a leading cause of death in people with anorexia.
Purging behaviors create a different but equally serious cardiac threat. Repeated vomiting or laxative misuse depletes potassium and other electrolytes that regulate heart rhythm. When potassium drops low enough, the heart can develop irregular rhythms that lead to cardiac arrest. In studies of people with bulimia, abnormally low potassium levels were found exclusively in those who purged, not in healthy controls.
Bone Density and Skeletal Health
Eating disorders cause rapid, significant bone loss. Among adults with anorexia nervosa, 92% have reduced bone density and 38% meet the criteria for osteoporosis at one or more skeletal sites. These aren’t numbers typically seen until decades later in life. Adolescents fare somewhat better but are still affected during a period that should be their peak bone-building years: up to 50% of adolescent girls with anorexia have measurably reduced bone density, and the numbers are even worse for boys, with 70% showing compromised bone at one or more sites.
Without recovery, bone density drops by roughly 2.5% per year at both the spine and hip. With weight restoration and the return of menstrual periods, that trend reverses to a gain of about 3% per year at the spine and 2% at the hip. But recovery doesn’t always bring bones fully back to normal, and the window of adolescent bone growth, once missed, can’t be fully recaptured.
Brain Structure Changes
Malnutrition physically shrinks the brain. Imaging studies of adolescents with anorexia show reduced grey matter volume in areas responsible for emotion processing, memory, decision-making, and body awareness. This includes regions involved in appetite regulation, reward processing, and the ability to accurately perceive one’s own body, which helps explain why the disorder is so self-reinforcing.
The encouraging finding is that some of this damage reverses with weight restoration. After treatment, grey matter volume in several key brain regions returned to near-normal levels, and that physical recovery correlated with improvements in eating-related anxiety and body image distortion. However, certain areas, particularly those involved in impulse control, habit formation, and some memory functions, did not recover in the short term. This may partly explain why relapse rates remain high even after initial treatment succeeds.
Digestive System Complications
Gastrointestinal problems are among the most common and most distressing effects, and they often create a vicious cycle. Restriction slows the entire digestive tract. The stomach loses its ability to contract normally and empty food at a healthy pace, a condition called gastroparesis. The result is intense bloating, nausea, and feeling uncomfortably full after eating very small amounts. These symptoms can make the refeeding process during recovery feel physically unbearable, which is one reason nutritional rehabilitation requires careful medical supervision.
About two-thirds of people with anorexia develop slow colonic transit, meaning food moves through the intestines much more slowly than normal, and over 40% develop pelvic floor dysfunction that further contributes to constipation. For those with bulimia, vomiting was reported by 100% of patients in one clinical sample, and satiation and bloating were significantly higher across all eating disorder types compared to healthy volunteers.
Teeth and Oral Health
Frequent vomiting bathes teeth in stomach acid, and the damage follows a distinctive pattern. The inner surfaces of the upper front teeth take the worst hit, as they sit directly in the path of vomit. Over time, the enamel dissolves and the tooth crowns can literally shell out, becoming thin and translucent. The palatal surfaces of upper teeth and the chewing surfaces of back teeth are the next most affected areas.
Erosive lesions visible on exam indicate the behavior has been happening for at least six months. This damage is irreversible: enamel doesn’t regenerate. Dentists are often the first health professionals to spot signs of bulimia because the erosion pattern, sometimes called perimolysis, is nearly always present in patients who purge by vomiting. It’s distinct enough that dental professionals are trained to recognize it as a red flag.
Reproductive and Hormonal Effects
Between 68% and 89% of women with anorexia lose their menstrual period for three months or longer during the course of their illness, and another 6 to 8% experience irregular cycles. This happens because the body suppresses reproductive hormones when it doesn’t have enough energy to sustain basic functions, let alone a pregnancy. The hormonal disruption also contributes directly to bone loss, since estrogen plays a protective role in maintaining bone density.
One genuinely reassuring finding: outcome studies have consistently shown that fertility rates in women with a lifetime history of anorexia nervosa do not differ from women in the general population once they recover. Menstrual periods typically return with adequate weight restoration, and the ability to conceive and carry a pregnancy returns with them.
Metabolic Effects of Binge Eating
Binge eating disorder, the most common eating disorder, carries its own set of physical consequences that look quite different from those of restrictive disorders. Repeated binge episodes are associated with higher rates of elevated blood fats (triglycerides) and a trend toward increased hypertension, even after accounting for body weight. This means the pattern of eating itself, not just any associated weight gain, contributes to cardiovascular risk factors. Over time, these metabolic shifts raise the likelihood of developing conditions like heart disease.
What Recovery Looks Like Physically
Many of the body’s systems begin repairing themselves once adequate nutrition is restored, but the timeline varies dramatically by organ. Electrolyte levels can normalize within days with proper medical support. Digestive function improves over weeks to months as the stomach and intestines readjust to normal food volumes and transit speeds. Correcting the underlying micronutrient deficiencies that accumulate during prolonged restriction or purging can take several weeks of careful nutritional support.
Bone density recovery is one of the slowest processes, measured in years rather than months, and may never fully reach what it would have been without the disorder. Brain volume recovery begins relatively quickly with weight restoration but, as noted, some regions lag behind. Heart rate and blood pressure typically improve as weight normalizes, though the timeline depends on how much cardiac muscle was lost.
The physical damage from eating disorders is real and measurable, but the body’s capacity to heal is significant when recovery begins. The earlier intervention happens, the more reversible the damage tends to be, particularly for adolescents whose bodies are still developing.