Author: Logan Strouther, MSc, BACP (Accred.) Eating Disorder Specialist
A Clinical Information Resource
Anorexia nervosa is a serious mental health condition characterised by persistent restriction of energy intake, intense concerns about weight, shape, or eating, and behaviours that interfere with maintaining a healthy body weight. Prolonged malnutrition affects virtually every system of the body and can result in significant physical and psychological complications. The severity of these complications often increases with the duration and severity of the illness. While many effects improve with nutritional rehabilitation and recovery, some may persist long-term, particularly when the illness has been present for an extended period. Without appropriate treatment, some complications can be life-threatening.
Dermatological and Integumentary Effects
As weight loss and nutritional deprivation occur, individuals with anorexia nervosa often experience noticeable changes to their hair, skin, and nails. During starvation, blood flow to the extremities slows as the body attempts to conserve energy and maintain core body temperature. This may result in cold intolerance and a bluish discolouration of the fingers, toes, ears, or nose, known as acrocyanosis (Brown & Mehler, 2017).
To help preserve body heat, the body may produce lanugo, a fine, soft hair that develops on areas such as the face, arms, back, and torso. In contrast, scalp hair may become thin, brittle, or begin to fall out due to inadequate nutrient intake. Nails may also become fragile, break easily, or develop ridges.
Gastrointestinal Effects
As nutritional intake decreases and weight loss progresses, many individuals experience gastroparesis, or delayed emptying of the stomach. Food moves more slowly through the digestive tract, often leading to bloating, abdominal discomfort, early fullness, nausea, constipation, and infrequent bowel movements. These symptoms occur because starvation slows gastrointestinal motility and reduces the normal functioning of the digestive system (Brown & Mehler, 2017).
The colon may also become less effective at moving waste through the body, contributing to chronic constipation. These gastrointestinal symptoms can be distressing and may inadvertently reinforce restrictive eating behaviours.
If purging behaviours are present, additional complications can occur. Self-induced vomiting may lead to erosion of tooth enamel, dental decay, inflammation of the oesophagus, and, in severe cases, tears in the oesophageal lining. Laxative misuse may damage the normal functioning of the colon and contribute to electrolyte disturbances.
Endocrine System Effects
Prolonged food restriction and excessive exercise can significantly alter the body’s normal energy regulation processes. As glycogen stores become depleted, the body adapts by conserving energy and altering glucose metabolism. In severe cases, individuals may develop hypoglycaemia (low blood glucose levels), which can cause headaches, slowed thinking, mood changes, dizziness, poor concentration, impaired balance, seizures, and, in rare circumstances, death (Brown & Mehler, 2017).
Hormonal functioning is frequently disrupted in individuals with anorexia nervosa. Levels of reproductive hormones such as oestrogen and testosterone commonly decrease, which may affect libido, fertility, bone health, and overall physical functioning. Many women experience irregular or absent menstrual periods; however, some may continue to ovulate despite changes in their menstrual cycle. As a result, pregnancy remains possible even when menstruation has stopped.
In adolescents, hormonal disruption may interfere with normal growth and pubertal development, potentially affecting height, bone development, and long-term physical health.
Nervous System Effects
Malnutrition can have a profound impact on the brain and nervous system. Neuroimaging studies have demonstrated reductions in both grey and white matter volume during periods of significant malnutrition (Brown & Mehler, 2017). These changes may contribute to difficulties with concentration, memory, learning, decision-making, emotional regulation, and cognitive flexibility.
Individuals may experience slowed thinking, mental fatigue, poor concentration, memory difficulties, irritability, and increased emotional sensitivity. In severe cases, malnutrition and associated metabolic disturbances may contribute to confusion, seizures, and altered levels of consciousness.
These neurological changes can significantly affect day-to-day functioning. Many individuals with anorexia nervosa place a high value on academic achievement, work performance, or productivity (perfectionism). However, the effects of starvation on the brain can make it increasingly difficult to concentrate, process information efficiently, solve problems, and maintain attention.
Encouragingly, research suggests that many of these structural and functional brain changes improve substantially following nutritional rehabilitation and sustained recovery. Improvements in concentration, memory, cognitive functioning, and emotional processing are commonly observed as physical health is restored (Roberto et al., 2010).
Skeletal System Effects
Reduced bone density is one of the most common long-term medical complications of anorexia nervosa. Individuals with the illness are at significantly increased risk of developing osteopenia and osteoporosis, conditions that weaken bones and increase the likelihood of fractures (Brown & Mehler, 2017).
Several factors contribute to this reduction in bone density, including chronic malnutrition, low body weight, reduced energy availability, and decreased levels of hormones such as oestrogen and testosterone. The risk is particularly concerning during adolescence and early adulthood, when peak bone mass would normally be developing.
As bones become weaker and more fragile, individuals may experience stress fractures, fractures from relatively minor injuries, and chronic musculoskeletal pain. In some cases, reductions in bone density may persist even after recovery, highlighting the importance of early intervention and treatment.
Cardiovascular Effects
One of the most common medical complications of anorexia nervosa is bradycardia, an abnormally slow heart rate. This occurs as the body attempts to conserve energy during periods of prolonged starvation. Individuals may also experience low blood pressure, dizziness, fatigue, fainting episodes, cold extremities, and reduced exercise tolerance (Brown & Mehler, 2017).
Over time, malnutrition can lead to a reduction in cardiac muscle mass, causing the heart to become smaller and less efficient. As cardiac output decreases, individuals may experience weakness, shortness of breath, chest discomfort, and reduced physical endurance.
Electrolyte imbalances, particularly among individuals who engage in purging behaviours, can further increase the risk of potentially life-threatening cardiac arrhythmias. Disturbances in potassium, magnesium, and phosphate levels may affect the heart’s electrical activity and contribute to irregular heart rhythms.
Cardiovascular complications remain one of the leading causes of death associated with anorexia nervosa. Severe malnutrition, electrolyte disturbances, and cardiac rhythm abnormalities can all contribute to sudden cardiac events. For this reason, ongoing medical monitoring is an essential component of treatment and recovery.
Metabolic and Refeeding Complications
Individuals who have experienced prolonged malnutrition may be at risk of refeeding syndrome during nutritional rehabilitation. Refeeding syndrome occurs when the reintroduction of nutrition causes rapid shifts in fluids and electrolytes, particularly phosphate, potassium, and magnesium.
Without appropriate medical monitoring, these changes can result in serious complications affecting the heart, lungs, nervous system, and other vital organs. Symptoms may include weakness, breathing difficulties, cardiac complications, confusion, and, in severe cases, death. Careful and structured nutritional rehabilitation is therefore essential for individuals who are severely malnourished.
Conclusion
Anorexia nervosa affects far more than body weight. The physical consequences of prolonged malnutrition can impact nearly every organ system, including the skin, digestive system, endocrine system, brain, bones, and cardiovascular system. While many of these complications improve with appropriate treatment, nutritional rehabilitation, and sustained recovery, some effects may persist long-term. Early intervention and comprehensive treatment are therefore critical to reducing medical risk and supporting both physical and psychological recovery.
References
Brown, C. A., & Mehler, P. S. (2017). Medical complications of anorexia nervosa and their treatments: An update on some critical aspects. Eating and Weight Disorders, 22(4), 537–547.
Roberto, C. A., Mayer, L. E., Brickman, A. M., Barnes, A., Muraskin, J., Yeung, L. K., Steffener, J., Stern, Y., & Walsh, B. T. (2010). Brain tissue volume changes following weight gain in adults with anorexia nervosa. International Journal of Eating Disorders, 44(5), 406–411.
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