Eating disorders affect nearly every system in the body, from the heart and bones to the brain and digestive tract. The damage depends on the type of disorder and how long it persists, but even short periods of disordered eating can trigger measurable changes. Anorexia nervosa carries a mortality rate roughly six times higher than expected for the general population, making it one of the deadliest mental health conditions.
Heart and Cardiovascular Effects
Malnutrition from anorexia causes the heart muscle itself to shrink. As the body loses mass, so does the heart, and the result is a dangerously slow resting heart rate, a condition called bradycardia, where the heart drops below 60 beats per minute. One specialist described the process bluntly: “The heart atrophies. It slows down like a bear that’s hibernating. And that can turn into dangerous rhythms.”
Purging behaviors in bulimia create a different kind of cardiac risk. Repeated vomiting and laxative or diuretic misuse drain the body of potassium and other electrolytes. When potassium drops too low, the electrical signals that keep the heart beating in rhythm become unstable. This can cause a prolonged QT interval on a heart monitor and, in serious cases, life-threatening arrhythmias.
Many people with eating disorders also develop postural orthostatic tachycardia syndrome (POTS), where standing up causes a rapid heartbeat, dizziness, lightheadedness, and palpitations because not enough blood returns to the heart. This can make everyday activities like getting out of bed or showering feel exhausting.
Bone Density and Fracture Risk
Eating disorders, particularly anorexia, interfere with the hormones that build and maintain bone. In women, disruption across multiple hormone pathways alters bone metabolism, especially at the spine and hip. For adolescents, this timing is especially damaging because the teenage years are when bone density is supposed to peak. Falling short during that window sets the stage for osteoporosis and fractures that can persist for decades.
The numbers are stark. A large matched cohort study found that anorexia was associated with a 7.5 times higher risk of osteoporotic fractures compared to people without the disorder. In men, the effects are similarly lasting: male patients with eating disorders were at least 1.8 times more likely to experience osteoporotic fractures, hip fractures, and other fractures up to 20 years after diagnosis.
Digestive System Damage
The digestive tract takes a direct hit from both restriction and purging. One common complication is gastroparesis, where the stomach empties food into the small intestine far too slowly. This happens when the vagus nerve, which controls the movement of food through the digestive tract, becomes damaged or stops functioning properly. The result is persistent bloating, nausea, and early fullness that can make eating feel physically uncomfortable, creating a vicious cycle that reinforces the disorder.
Chronic laxative abuse can weaken the colon’s ability to move waste on its own, leading to severe constipation that persists even after laxative use stops. For people who purge by vomiting, repeated exposure of the esophagus to stomach acid raises the risk of tears and, in rare cases, rupture.
Dental and Oral Health
Repeated vomiting bathes the teeth in gastric acid, producing a characteristic pattern of erosion called perimolysis. The acid dissolves enamel without any bacterial involvement. It typically starts on the inner surfaces of the upper front teeth and spreads to the biting surfaces of the back teeth. Over time, teeth become visibly shortened, thin at the edges, and lose their normal shine. Existing fillings may start to stand out above the surrounding tooth surface because the enamel around them has worn away.
Beyond appearance, the erosion causes real discomfort. Tooth sensitivity increases as protective enamel disappears, and in advanced cases, the inner pulp of the tooth can become exposed. The damage is largely irreversible once it occurs.
Hormonal and Reproductive Effects
Eating disorders disrupt the chain of hormonal signals between the brain and the ovaries. In anorexia, the combination of low energy availability, depleted fat stores, and reduced levels of key signaling molecules like leptin throws off the normal pulsing release of luteinizing hormone. The result is a state called hypogonadotropic hypogonadism, where the brain essentially stops telling the ovaries to function. Periods become irregular or disappear entirely.
Bulimia can cause the same hormonal suppression, even in people who are not significantly underweight. Although amenorrhea was removed from the formal diagnostic criteria for eating disorders, menstrual disturbances remain one of the most common physical signs. These hormonal disruptions also feed directly into the bone density loss described above, since estrogen plays a critical role in maintaining bone strength.
Brain Structure and Function
Chronic malnutrition and disordered eating patterns physically alter the brain. Research using brain imaging has found that people with bulimia show changes in gray matter volume across several regions involved in decision-making, reward processing, and impulse control. Specifically, areas responsible for evaluating food cues and external eating triggers show increased volume and altered connectivity with other brain regions.
These structural changes are not just academic findings. They help explain why eating disorders feel so compulsive. The brain’s reward circuitry becomes reorganized in ways that reinforce disordered behavior, making recovery feel like fighting against your own wiring. In binge eating disorder, heightened dopamine signaling in reward-related brain pathways may drive the compulsive, uncontrollable eating episodes that define the condition.
Metabolic Effects of Binge Eating Disorder
Binge eating disorder (BED) carries its own distinct set of physical consequences, separate from anorexia and bulimia. An estimated 60% of obese patients with BED meet criteria for metabolic syndrome, a cluster of conditions that includes high blood pressure, elevated blood sugar, excess body fat around the waist, and abnormal cholesterol levels. BED is associated with higher triglyceride levels at all body weights, not just in people who are overweight.
The metabolic damage goes beyond what weight gain alone would cause. Consuming large quantities of food in a short period triggers spikes in oxidative and inflammatory stress. People with BED show elevated levels of inflammatory markers in their blood, which over time contribute to insulin resistance, type 2 diabetes, and cardiovascular disease. Patterns common in BED, like meal skipping and repeated weight cycling, are themselves independent predictors of metabolic syndrome regardless of body size.
Mortality Risk
Eating disorders are fatal more often than most people realize. A meta-analysis published in The British Journal of Psychiatry found that people with anorexia nervosa had a standardized mortality ratio of 6.2, meaning they died at more than six times the rate of the general population. The risk was elevated for nearly every category of death, both medical and external.
Of 265 observed deaths in the study, the single most common cause was suicide, accounting for 84 deaths. Anorexia itself was listed as the direct cause in 39 cases, and cancer in 29. The suicide rate alone was nearly 14 times higher than expected. Substance use disorders, which frequently co-occur with eating disorders, carried the second-highest excess mortality. These numbers underscore that eating disorders are not phases or lifestyle choices. They are serious medical conditions with consequences that accumulate across every organ system in the body.