Reviewed by Amy Baker Dennis, PhD, FAED
Anorexia nervosa is an eating disorder characterized by weight loss (or lack of appropriate weight gain in growing children); difficulties maintaining an appropriate body weight for height, age, and stature; and, in many individuals, distorted body image. People with anorexia nervosa generally restrict the number of calories and the types of food they eat. Some people with the disorder also exercise compulsively, purge via vomiting and laxatives, and/or binge eat.
Anorexia nervosa can affect people of all ages, genders, sexual orientations, races, and ethnicities. Historians and psychologists have found evidence of people displaying symptoms of anorexia for hundreds of years.1
Although the disorder most frequently begins during adolescence, an increasing number of children and older adults are also being diagnosed with anorexia nervosa.2,3 You cannot tell if a person is struggling with anorexia nervosa by looking at them.
To be diagnosed with anorexia nervosa (AN) according to the DSM-5 TR, the following criteria must be met:4
- Restriction of energy intake relative to requirements leading to a significantly low body weight in the context of age, sex, developmental trajectory, and physical health.
- Intense fear of gaining weight or becoming fat, even though underweight.
- Disturbance in the way in which one’s body weight or shape is experienced, undue influence of body weight or shape on self-evaluation, or denial of the seriousness of the current low body weight.
Even if all the DSM-5 criteria for anorexia nervosa are not met, a serious eating disorder can still be present. Atypical anorexia includes those individuals who meet the criteria for anorexia but who are not underweight despite significant weight loss. Research studies have not found a difference in the medical and psychological impacts of anorexia nervosa and atypical anorexia nervosa.
Warning Signs and Symptoms of Anorexia Nervosa
Please note that even though these are common symptoms not everyone with anorexia nervosa displays all of these emotional and behavioral symptoms.
Emotional and Behavioral Signs and Symptoms:4
- Dramatic weight loss
- Has disturbed experience of body weight or shape, undue influence of weight or shape on self-evaluation, or denial of the seriousness of low body weight
- Dresses in layers to hide weight loss and/or stay warm
- Is preoccupied with weight, food, calories, fat grams, and dieting
- Refuses to eat certain foods, and often eliminates whole food groups (carbohydrates, fats, etc.)
- Makes frequent comments about feeling “fat” or being a higher weight despite weight loss
- Has intense fear of weight gain, even though underweight
- Complains of constipation, abdominal pain, cold intolerance, lethargy, and/or excess energy
- Denies feeling hungry
- Develops food rituals (e.g., eating foods in certain orders, excessive chewing, rearranging food on a plate)
- Uses excessive amounts of condiments, spices, and artificial sweeteners
- Consumes large amounts of water, diet beverages and caffeine drinks to fluid load and reduce hunger.
- Cooks meals for others without eating
- Makes excuses to avoid mealtimes or situations involving food
- Expresses a need to “burn off” calories taken in
- Maintains an excessive, rigid exercise regimen – despite weather, fatigue, illness, or injury
- Withdraws from friends and previously pleasurable activities and becomes more isolated and secretive.
- Has limited social spontaneity
- Resists or is unable to maintain a body weight appropriate for their age, height, and build
- Displays rigid and inflexible thinking style and has difficulty adapting to change
Physical Signs and Symptoms:4
- Stomach cramps, other non-specific gastrointestinal complaints (constipation, acid reflux, etc.)
- Difficulties concentrating
- Abnormal laboratory findings (anemia, low thyroid and hormone levels, low potassium, low blood cell counts, slow heart rate), though some people with anorexia nervosa do not have any laboratory abnormalities
- Feeling cold all the time
- Sleep problems
- Menstrual irregularities, primary or secondary amenorrhea (not starting the menstrual cycle or the loss of the menstrual cycle) or only experiencing a period when taking hormonal supplements
- Post puberty female loses menstrual period
- Cuts and calluses across the top of finger joints (a result of inducing vomiting)
- Dental problems due to purging includes erosion of enamel; bleeding gums/periodontal disease; temperature sensitivity; cavities; discoloration of teeth; dry mouth; enlarged parotid/submandibular glands and swallowing problems
- Dry skin
- Dry and brittle nails
- Swelling around area of salivary glands
- Fine hair on body (lanugo)
- Thinning of hair on head, dry and brittle hair
- Muscle weakness
- Yellow skin (in context of eating large amounts of carrots)
- Cold, mottled hands and feet or swelling of feet and ankles
- Poor wound healing
Frequent Co-Occurring Conditions
The following are some conditions that frequently co-occur with anorexia nervosa:5
- Anxiety disorders including generalized anxiety disorder, social anxiety, phobias, panic disorder, post-traumatic stress disorder, and obsessive-compulsive disorder
- Depression and other mood disorders
- Substance use disorders
Health Consequences of Anorexia Nervosa
In anorexia nervosa’s cycle of self-starvation, the body is denied the essential nutrients it needs to function normally. Thus, the body is forced to slow down all of its processes to conserve energy, resulting in serious medical consequences.6
The body is generally resilient at coping with the stress of eating disordered behaviors, and laboratory tests can generally appear perfect even as someone is at high risk of death. Electrolyte imbalances can kill without warning; so can cardiac arrest.6 Therefore, it’s incredibly important to understand the many ways that eating disorders affect the body.
- Consuming fewer calories than you need means that the body breaks down its own tissue to use for fuel. Muscles are some of the first organs broken down, and the most important muscle in the body is the heart. Pulse and blood pressure begin to drop as the heart has less fuel to pump blood and fewer cells to pump with. The risk for heart failure rises as the heart rate and blood pressure levels sink lower and lower.
- Some physicians confuse the slow pulse of an athlete (which is due to a strong, healthy heart) with the slow pulse of an eating disorder (which is due to a malnourished heart). If there is concern about an eating disorder, consider low heart rate to be a symptom.
- Purging by vomiting or laxatives depletes your body of important chemicals called electrolytes. The electrolyte potassium plays an important role in helping the heart beat and muscles contract, but is often depleted by purging. Other electrolytes, such as sodium and chloride, can also become imbalanced by purging or by drinking excessive amounts of water. Electrolyte imbalances can lead to irregular heartbeats and possibly heart failure and death.
- Reduced resting metabolic rate, a result of the body’s attempts to conserve energy.
- Slowed digestion known as gastroparesis. Food restriction and/or purging by vomiting interferes with normal stomach emptying and the digestion of nutrients, which can lead to:
- Stomach pain and bloating
- Nausea and vomiting
- Blood sugar fluctuations
- Blocked intestines from solid masses of undigested food
- Bacterial infections
- Feeling full after eating only small amounts of food
- Constipation, which can have several causes:
- Inadequate nutritional intake, which means there’s not enough in the intestines for the body to try and eliminate
- Long-term inadequate nutrition can weaken the muscles of the intestines and leave them without the strength to propel digested food out of the body
- Laxative abuse can damage nerve endings and leave the body dependent on them to have a bowel movement
- Binge eating can cause the stomach to rupture, creating a life-threatening emergency.
- Vomiting can wear down the esophagus and cause it to rupture, creating a life-threatening emergency.
- Frequent vomiting can also cause sore throats and a hoarse voice
- When someone makes themselves vomit over a long period of time, their salivary (parotid) glands under the jaw and in front of the ears can get swollen. This can also happen when a person stops vomiting.
- Both malnutrition and purging can cause pancreatitis, an inflammation of the pancreas. Symptoms include pain, nausea, and vomiting
- Intestinal obstruction, perforation, or infections, such as:
- Mechanical bowel problems, like physical obstruction of the intestine, caused by ingested items.
- Intestinal obstruction or a blockage that prevents food and water from passing through the intestines.
- Bezoar, a mass of indigestible material found trapped in the gastrointestinal tract (esophagus, stomach, or intestines)
- Intestinal perforation, caused by the ingestion of a nonfood item that creates a hole in the wall of the stomach, intestines or bowels
- Infections such as toxoplasmosis and toxocariasis may occur because of ingesting feces or dirt
- Although the brain weighs only three pounds, it consumes up to one-fifth of the body’s calories. Dieting, fasting, self-starvation, and/or erratic eating means the brain isn’t getting the energy it needs, which can lead to obsessing about food and difficulties concentrating.
- Extreme hunger or fullness at bedtime can create difficulties falling or staying asleep.
- The body’s neurons require an insulating, protective layer of lipids to be able to conduct electricity. Inadequate fat intake can damage this protective layer, causing numbness and tingling in hands, feet, and other extremities.
- Neurons use electrolytes (potassium, sodium, chloride, and calcium) to send electrical and chemical signals in the brain and body. Severe dehydration and electrolyte imbalances can lead to seizures and muscle cramps.
- If the brain and blood vessels can’t push enough blood to the brain, it can cause fainting or dizziness, especially upon standing.
- Individuals of higher body weights are at increased risk of sleep apnea, a disorder in which a person regularly stops breathing while asleep.
- The body makes many of its needed hormones with the fat and cholesterol we eat. Without enough fat and calories in the diet, levels of hormones can fall, including:
- Sex hormones estrogen and testosterone
- Thyroid hormones
- Lowered sex hormones can cause menstruation to fail to begin, to become irregular, or to stop completely.
- Lowered sex hormones can significantly increase bone loss (known as osteopenia and osteoporosis) and the risk of broken bones and fractures.
- Reduced resting metabolic rate, a result of the body’s attempts to conserve energy.
- Over time, binge eating can potentially increase the chances that a person’s body will become resistant to insulin, a hormone that lets the body get energy from carbohydrates. This can lead to Type 2 Diabetes.
- Without enough energy to fuel its metabolic fire, core body temperature will drop and hypothermia may develop.
- Starvation can cause high cholesterol levels, although this is NOT an indication to restrict dietary fats, lipids, and/or cholesterol.
Other Health Consequences6
- Low caloric and fat consumption can cause dry skin, and hair to become brittle and fall out.
- To conserve warmth during periods of starvation, the body will grow fine, downy hair called lanugo.
- Severe, prolonged dehydration can lead to kidney failure.
- Inadequate nutrition can decrease the number of certain types of blood cells.
- Anemia develops when there are too few red blood cells or too little iron in the diet. Symptoms include fatigue, weakness, and shortness of breath.
- Malnutrition can also decrease infection-fighting white blood cells.
Treating anorexia nervosa requires working with a multidisciplinary team of health and mental health professionals who have expertise in treating this type of eating disorder. The treatment team may include a physician, psychiatrist, psychotherapist, and dietician.7 Given the serious physical and psychological consequences that can result from anorexia nervosa it is essential to seek professional help as soon as possible. Early intervention has also been shown to be an important factor in positive treatment outcomes.5
Special thank you to Walter Kaye, MD, Professor of Psychiatry, Director, UCSD Eating Disorder Research and Treatment Program, University of California, San Diego
 Dell’Osso, L., Abelli, M., Carpita, B., Pini, S., Castellini, G., Carmassi, C., & Ricca, V. (2016). Historical evolution of the concept of anorexia nervosa and relationships with orthorexia nervosa, autism, and obsessive-compulsive spectrum. Neuropsychiatric disease and treatment, 12, 1651–1660. https://doi.org/10.2147/NDT.S108912
 van Eeden, A. E., van Hoeken, D., & Hoek, H. W. (2021). Incidence, prevalence and mortality of anorexia nervosa and bulimia nervosa. Current opinion in psychiatry, 34(6), 515–524. https://doi.org/10.1097/YCO.0000000000000739
 Samuels, K. L., Maine, M. M., & Tantillo, M. (2019). Disordered Eating, Eating Disorders, and Body Image in Midlife and Older Women. Current psychiatry reports, 21(8), 70. https://doi.org/10.1007/s11920-019-1057-5
 American Psychiatric Association. (2022). Diagnostic and statistical manual of mental disorders: DSM-5-TR. American Psychiatric Association Publishing. https://doi.org/10.1176/appi.books.9780890425787
 Hambleton, A., Pepin, G., Le, A., Maloney, D., National Eating Disorder Research Consortium, Touyz, S., & Maguire, S. (2022). Psychiatric and medical comorbidities of eating disorders: findings from a rapid review of the literature. Journal of eating disorders, 10(1), 132. https://doi.org/10.1186/s40337-022-00654-2
 Cost, J., Krantz, M. J., & Mehler, P. S. (2020). Medical complications of anorexia nervosa. Cleveland Clinic Journal of Medicine, 87(6), 361–366. https://doi.org/10.3949/ccjm.87a.19084
 Crone, C., Anzia, D. J., Fochtmann, L. J., & Dahl, D. (2023). The American Psychiatric Association practice guideline for the treatment of patients with eating disorders, Fourth Edition. American Psychiatric Association. Available at: https://psychiatryonline.org/doi/book/10.1176/appi.books.9780890424865