Anorexia nervosa is a complex eating disorder and serious mental health condition that affects millions of people worldwide, characterized by extreme restriction of food intake, intense fear of weight gain, and distorted body image, often leading to dangerously low body weight and severe health complications.

Understanding Anorexia Nervosa

Anorexia nervosa, often simply called anorexia, is much more than concerns about weight or appearance. It is a treatable eating disorder in which people maintain a significantly low body weight relative to their personal weight history, and this restriction becomes an all-consuming force in their lives. While many people with anorexia appear very thin, some may not look underweight at first glance, and others may appear overweight to themselves despite actually having lost significant weight or failed to gain needed weight^[2].

The disorder involves severe limitation of the amount or type of food consumed, often accompanied by an intense fear of gaining weight. Many people with anorexia place extremely high value on controlling their weight and shape, using extreme efforts that can greatly harm their quality of life and physical health. What makes this condition particularly challenging is that it causes changes in the brain due to poor nutrition, which means continuing the risky behavior is not truly a choice—the illness fundamentally alters how a person thinks and perceives themselves^[2].

In medical terminology, “anorexia” means not wanting to eat, but adding “nervosa” transforms it into a mental health condition rooted in the nervous system—in the brain, nerves, impulses, and thoughts. It develops from negative thoughts and feelings about eating, weight, and body image that, unlike typical concerns, become so extreme they can oppress a person and lead to serious consequences for both mental and physical health^[4].

Types of Anorexia Nervosa

Anorexia nervosa presents in different forms based on the specific behaviors involved. Understanding these types helps healthcare professionals tailor treatment approaches to individual needs^[4][7].

Restrictive anorexia involves severe calorie restriction alone. People with this type limit the amount and type of food they eat through behaviors like counting calories obsessively, skipping meals, limiting or avoiding certain food groups such as carbohydrates, or following rigid rules like only eating foods of a certain color. These restrictive behaviors are often accompanied by excessive exercise^[7].

Binge-purge anorexia involves calorie restriction combined with episodes of binge eating and purging, similar to bulimia nervosa. Purging behaviors might include self-induced vomiting, misuse of laxatives, diuretics, or enemas, or extensive exercising. Some people may binge eat—consuming a large amount of food while feeling out of control—and then attempt to compensate through purging^[4][7].

Atypical anorexia nervosa is a form of eating disorder classified as Other Specified Feeding or Eating Disorders. In this type, individuals display all the behavioral patterns and psychological features of anorexia nervosa, but their body mass index remains normal or above normal. This makes the condition harder to recognize, as the person may not appear underweight despite engaging in severe restriction and having the same mental health struggles^[4][7].

Epidemiology: Who Is Affected

Anorexia nervosa affects a substantial number of people across the globe, though exact prevalence varies depending on the population studied. In the United States alone, nearly 30 million Americans will experience an eating disorder in their lifetime^[1]. Research indicates that the lifetime prevalence of anorexia nervosa ranges from 0.3% to 1% of adults in the United States, though some European studies have demonstrated higher rates of 2% to 4%^[8].

The disorder is significantly more common in females than males, with women and girls bearing the majority of cases. The typical onset occurs during late adolescence and early adulthood, making teenagers and young adults particularly vulnerable. However, this does not mean anorexia is limited to these groups—men and people of any age can develop the condition, and it affects individuals across all cultures, ethnicities, and racial backgrounds^[5][8].

Anorexia nervosa carries one of the highest mortality rates of any mental health disorder. It has the second-highest death rate among all mental illnesses, surpassed only by opioid overdoses. Most deaths related to anorexia stem from heart conditions caused by severe malnutrition or from suicide, underscoring the life-threatening nature of this illness^[2].

Causes of Anorexia Nervosa

There is no single cause of anorexia nervosa. Instead, researchers understand that the disorder develops through a complex interaction of biological, psychological, and social factors. This multifaceted origin means that different people may develop anorexia through different pathways, though certain patterns are commonly observed^[4][5].

From a biological perspective, scientists have observed significant differences in brain structure and function among people with anorexia. These individuals often have altered levels of important neurotransmitters—chemical messengers in the brain—such as serotonin and dopamine. Serotonin affects impulse control and aspects of personality like neuroticism, while dopamine influences eating behavior and the brain’s reward system. These chemical imbalances can affect appetite, mood, and impulse control in ways that contribute to the development and maintenance of anorexia^[4][8].

Genetics plays a substantial role as well. Studies show genetic correlations between anorexia and traits like educational attainment, neuroticism, and even schizophrenia. Having a first-degree relative—a parent or sibling—with an eating disorder significantly raises a person’s risk of developing one themselves. Part of this risk comes from genes inherited at birth, but family environment also matters. The values and habits learned while growing up, including attitudes about food, weight, and appearance, can contribute to the development of eating disorders^[4][8].

Psychological factors form another crucial component. People who develop anorexia often struggle with low self-esteem or feel that their self-worth depends heavily on controlling their body weight. Having co-existing mental health conditions such as major depressive disorder or generalized anxiety disorder is common among those with anorexia, suggesting overlapping vulnerabilities in brain function and emotional regulation^[4][8].

Social and environmental pressures cannot be overlooked. The success of many professions—including modeling, acting, ballet, long-distance running, and martial arts—often depends on maintaining a lean body weight. Media outlets constantly promote diet tips and weight loss secrets, while social media amplifies messages linking thinness with beauty, success, and self-control. Teenagers, who can be particularly judgmental of themselves and one another, face intense peer pressure regarding appearance. These societal messages create an environment where restrictive eating behaviors may initially seem like a path to acceptance or achievement^[4][8].

Risk Factors

While anyone can develop anorexia nervosa, certain factors increase the likelihood of developing this condition. Understanding these risk factors can help with early identification and intervention^[8].

Being female is one of the strongest demographic risk factors, though males are certainly not immune. Personality traits also play a role—individuals who are perfectionistic or highly impulsive appear more vulnerable to eating disorders. People who experienced childhood obesity may later develop anorexia as they attempt to control their weight through increasingly extreme measures^[8].

Having existing mood disorders increases risk substantially. The presence of depression, anxiety disorders, or other mental health conditions creates vulnerability for developing anorexia. A history of sexual abuse or trauma also raises the risk, as some individuals may use eating restriction as a way to cope with overwhelming emotions or to exert control over their bodies^[8].

Certain professions and activities that emphasize body weight or appearance carry elevated risk. Athletes, particularly those in sports like gymnastics, figure skating, wrestling, or distance running, face pressure to maintain specific weights. Dancers, models, and actors who base their careers on physical appearance are similarly vulnerable. Within these environments, weight-related concerns from coaches, directors, or peers can trigger or worsen restrictive eating behaviors^[4][8].

Family environment matters as well. Growing up in a household where there is excessive focus on weight, dieting, or appearance can normalize restrictive eating patterns. Additionally, the general peer environment during adolescence, when teenagers are developing their identities and are particularly sensitive to social feedback, can contribute to the development of anorexia^[4].

Symptoms and Signs

Anorexia nervosa manifests through a wide range of physical, behavioral, and emotional symptoms. These signs can affect each person differently, and not everyone with anorexia will display all symptoms. However, recognizing these warning signs is crucial for early intervention^[4][5][7].

Physical Symptoms

The most visible physical sign is often significant weight loss over weeks or months, leading to below-average weight compared to height. In children and adolescents, the weight and height may be lower than the minimum expected for their age, or they may fail to gain weight as they should during growth periods. A body mass index of 18.5 or below is common in adults with anorexia^[4][5].

As malnutrition—the state of not getting the nutrients the body needs to stay healthy—progresses, additional physical symptoms emerge. These include extreme fatigue and physical weakness, making even simple activities exhausting. People often feel dizzy or lightheaded, and some experience fainting spells. Abnormal heart rhythms, called arrhythmias, can develop and are particularly dangerous^[4][5].

Other physical changes include feeling cold constantly, even in warm environments, because the body lacks sufficient energy to maintain normal temperature. Hair on the head may thin or fall out, while fine, downy hair may grow on the face and body as the body attempts to keep warm. Skin may become dry, yellow, or blotchy. Hands, arms, legs, or feet may swell. Women and girls commonly experience irregular periods or complete loss of menstruation, while males may experience decreased sex drive^[4][5][7].

Digestive problems are widespread, including feeling bloated, constipation, or developing food intolerances. The body struggles to process even small amounts of food after prolonged restriction. In cases where purging occurs, tooth enamel becomes worn and teeth increasingly sensitive and prone to decay from repeated exposure to stomach acid. The throat may be chronically inflamed and sore, and salivary glands in the neck and jaw can become swollen^[5][6].

Behavioral Symptoms

Behavioral changes often provide the earliest clues that someone is struggling with anorexia. These include missing meals or eating very little at mealtimes, thinking constantly about food, and being extremely careful about what to eat, such as avoiding any foods perceived as fattening. People with anorexia may count calories obsessively or strictly limit themselves to only certain types of food^[4][5].

They may cook elaborate meals for others while eating nothing themselves. Frequent weighing becomes ritualistic. Many withdraw from social events, especially those involving food, such as birthdays or holidays. Those who engage in purging behaviors consistently go to the bathroom immediately after eating. Some exercise compulsively for extended periods, especially after eating, continuing even when tired, sick, or injured^[4][5][15].

Misuse of substances designed to control weight is common. This includes overusing appetite suppressants, laxatives, diuretics (water pills), or diet aids in attempts to prevent weight gain from any food consumed^[4][5].

Emotional and Mental Symptoms

The psychological manifestations of anorexia are profound and distressing. A defining feature is a distorted body image—seeing oneself as fat even when at a healthy weight or severely underweight. This distorted perception is not simply low confidence; it reflects altered brain function caused by malnutrition and represents a genuine inability to recognize one’s true appearance^[5][7].

People with anorexia experience intense fear of gaining weight, often out of proportion to any realistic concern. They may have frequent critical thoughts and comments about their body weight and image. Many feel their self-worth depends entirely on controlling their weight^[4][5].

Mood changes are common and include listlessness, depression, or having a flat emotional range. Irritability increases, and many withdraw socially from friends and activities they once enjoyed. Difficulty sleeping disrupts rest, while concentration problems make it hard to focus on work or school. Interest in activities and hobbies diminishes, and life begins to revolve almost exclusively around food, eating, and weight^[15].

Prevention

While there is no guaranteed way to prevent anorexia nervosa, certain approaches may reduce risk, particularly when implemented early. Prevention efforts focus on building healthy attitudes toward food, body image, and self-worth from a young age.

Creating an environment at home where all body types are respected and where dieting is not glorified helps children develop healthier relationships with food. Parents and caregivers can model balanced eating behaviors and avoid making comments about their own or others’ weight or appearance. Emphasizing health, strength, and energy rather than thinness as goals helps shift focus away from appearance^[4].

Building self-esteem in children and teenagers through activities that are not appearance-based—such as academics, creative pursuits, or volunteer work—provides alternative sources of confidence and identity. Teaching young people to think critically about media messages regarding beauty and diet culture can help them resist unrealistic standards^[4].

Early intervention when warning signs appear is crucial. If someone begins showing concerning behaviors around food or expressing distorted thoughts about their body, getting professional help quickly provides the best chance for preventing full-blown anorexia or achieving faster recovery. Screening tools are available through organizations like the National Eating Disorders Association for people aged 13 and up who want to assess whether professional help may be needed^[1].

For those in high-risk professions or activities, such as athletes or performers, having access to mental health support and education about eating disorders can provide protective factors. Coaches, teachers, and mentors should be trained to recognize warning signs and to promote health over achieving unrealistic weight targets.

Pathophysiology: What Happens in the Body

Understanding what happens inside the body when someone has anorexia nervosa reveals why this disorder is so dangerous and why the behaviors become so difficult to change without treatment. The pathophysiology—the abnormal changes in body function that occur with disease—involves multiple organ systems and biochemical processes.

At the core of anorexia’s pathophysiology is severe caloric restriction that leads to a state of starvation. When the body does not receive adequate nutrition, it must adapt to survive. Initially, the body uses stored glucose for energy, but these stores deplete quickly. It then breaks down fat stores, but eventually begins breaking down muscle tissue, including the heart muscle, to obtain the amino acids and energy it needs^[2].

Brain changes are among the most significant alterations. The brain requires substantial energy to function properly, and malnutrition causes both structural and functional changes. Altered activity occurs in the corticolimbic system, which regulates appetite and fear responses. There is also diminished activity in the frontostriatal circuits, brain pathways that control habitual behaviors. These changes help explain why people with anorexia cannot simply “choose” to eat normally—their brains are literally functioning differently due to lack of nutrition^[8].

Neurotransmitter imbalances affect multiple aspects of mental and physical function. Decreased serotonin can worsen impulse control and increase anxiety and obsessive thoughts. Dopamine alterations affect the brain’s reward system, potentially making food less rewarding and restriction more compelling. These chemical changes perpetuate the disorder even when the person consciously wants to get better^[4][8].

The cardiovascular system suffers extensively. Heart rate slows, blood pressure drops, and the heart may develop dangerous irregular rhythms. The heart muscle can weaken and shrink, increasing risk of heart failure. Blood vessel function becomes impaired, leading to poor circulation and contributing to the constant feeling of being cold. Heart problems are a leading cause of death in severe anorexia^[5][6].

The skeletal system weakens as bones lose density, a condition called osteoporosis. This occurs because the body lacks calcium and other nutrients needed for bone health, and because hormonal changes affect bone formation. Weakened bones fracture easily and may never fully recover their strength, even with treatment^[5].

Hormonal systems go awry throughout the body. The reproductive system shuts down to conserve energy, causing menstrual periods to stop in females and decreased testosterone in males. Fertility problems can persist even after weight restoration. Thyroid function decreases, slowing metabolism further. The body produces stress hormones like cortisol in abnormal amounts^[5][7].

The digestive system becomes severely compromised. The stomach empties more slowly, causing uncomfortable fullness and bloating even from small amounts of food. Intestinal movement slows, leading to severe constipation. The liver may develop problems, and kidney function can deteriorate. In severe cases, if purging behaviors occur, electrolyte imbalances develop. Electrolytes—minerals like sodium, potassium, and calcium that must stay in careful balance—can become too low or too high, potentially causing stroke or heart attack^[5][6].

The immune system weakens, making it harder to fight off infections. Blood cell production decreases, potentially leading to anemia—a condition where the body doesn’t have enough healthy red blood cells to carry adequate oxygen to tissues. Severe dehydration can occur, especially with purging behaviors^[5][6].