What is Anorexia Nervosa?

Updated: Oct 6, 2020

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Anorexia nervosa (AN) is the fear of becoming fat and/or perceiving yourself as fat when you aren't necessarily so; it is characterized by weight loss or difficulty maintaining appropriate weight and often negative body image.

When I was starving myself, these descriptions fit me though I didn't meet the diagnosis criteria. I didn't eat because I didn't want to be fat, but I wasn't fat. To be diagnosed, an individual has to be at 15% less than their average body weight (see WebMD definition), and I wasn't. I don't think that is the best criteria to diagnose anorexia, but I understand the difficulty in identifying such a disease.

Diagnosis Criteria.

Credit to NEDA.

  1. Restriction of energy intake, energy intake lower than required for individuals' weight, height, physical health, and developmental stage

  2. Intense fear of gaining weight or becoming fat

  3. Irrational body image, the exaggerated influence of weight on self-worth, denial of the issue

Illness can be present without meeting all DSM-5 criteria. Atypical anorexia is when the patient meets all requirements, but isn't significantly underweight.


Credit to NEDA.

Emotional and behavioral

  • Dramatic weight loss

  • Dresses in layers to hide weight loss or stay warm

  • Is preoccupied with weight, food, calories, fat grams, and dieting

  • Refuses to eat certain foods, progressing to restrictions against whole categories of food (e.g., no carbohydrates, etc.)

  • Makes frequent comments about feeling "fat" or overweight despite weight loss

  • Complains of constipation, abdominal pain, cold intolerance, lethargy, and/or excess energy

  • Denies feeling hungry

  • Develops food rituals (e.g., eating foods in specific orders, excessive chewing, rearranging food on a plate)

  • Cooks meals for others without eating

  • Consistently 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  • Withdraws from usual friends and activities and becomes more isolated, withdrawn, and secretive

  • Seems concerned about eating in public

  • Has limited social spontaneity

  • Resists or is unable to maintain a body weight appropriate for their age, height, and build

  • Has intense fear of weight gain or being "fat," even though underweight

  • 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

  • Postpuberty female loses menstrual period

  • Feels ineffective

  • Has a strong need for control

  • Shows inflexible thinking

  • Has overly restrained initiative and emotional expression


  • Stomach cramps, other nonspecific 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)

  • Dizziness

  • Fainting/syncope

  • Feeling cold all the time

  • Sleep problems

  • Menstrual irregularities—amenorrhea, irregular periods or only having a period while on hormonal contraceptives (this is not considered a "true" period)

  • Cuts and calluses across the top of finger joints (a result of inducing vomiting)

  • Dental problems, such as enamel erosion, cavities, and tooth sensitivity

  • Dry skin

  • Dry and brittle nails

  • Swelling around the area of salivary glands

  • Fine hair on the body (lanugo)

  • Thinning of hair on the head, dry and brittle hair

  • Cavities, or discoloration of teeth, from vomiting

  • Muscle weakness

  • Yellow skin (in context of eating large amounts of carrots)

  • Cold, mottled hands and feet or swelling of feet

  • Poor wound healing

  • Impaired immune functioning


The exact cause of anorexia nervosa is unknown. Research has shown that there isn't one underlying cause for all AN cases, but a multitude of interchangeable reasons. Not one person is the same. Causes are physiological, biological, and environmental.


  • Studies have shown a link between anorexia and serotonin levels. Serotonin is a chemical in the brain that affects a variety of psychobiological factors, including hunger, anxiety, impulsivity, perception, and memory.

  • Weight issues can lead to AN. A history of dieting or weight problems can lead an individual to develop AN, though this is more specific to BED.


  • Eating patterns passed down from family members can affect a patient's relationship with food. If parents focus on food in a toxic way, the child is more likely to also.

  • Society's view on body image can also come into play. Unrealistic body images in magazines and television can increase a patient's desire to be thin. Weight stigma can have the same effect.

  • Lack of social networking can lead to AN. Patients with anorexia often report reduced social interactions and external support. Loneliness and isolation can lead to this eating disorder.

  • Bullying because of weight or otherwise can lead to an individual developing AN.


  • Other mental health disorders can lead to AN. Anorexia nervosa patients often have obsessive-compulsive disorder (OCD). The tendency of obsession can lead to an obsession with food and weight.

  • Emotional trauma can lead to AN. Stressful life events like divorce, abuse, or death can lead to the use of food as a coping mechanism.


In the 2007 study, Keski-Rahkonen and associates discovered that between 0.3-0.4% of young women and 0.1% of young men suffer from anorexia nervosa at any given point in time. They also found that 0.9% of women and 0.3% of men had anorexia during their life.

Keski-Rahkonen A, Hoek HW, Susser ES, Linna MS, Sihvola E, Raevuori A, …, and Rissanen A. (2007). Epidemiology and course of anorexia nervosa in the community. American Journal of Psychiatry, 164(8):1259-65. doi: 10.1176/appi. Ajp.2007.06081388.

In the study "Eating Disorders", researchers found that between 0.9% and 2.0% of females and 0.1% to 0.3% of males will develop anorexia. Subthreshold anorexia occurs in 1.1% to 3.0% of adolescent females.

Stice E & Bohon C. (2012). Eating Disorders. In Child and Adolescent Psychopathology, 2nd Edition, Theodore Beauchaine & Stephen Linshaw, eds. New York: Wiley.

When researchers followed a group of 496 adolescent girls for eight years, until they were 20, they found 5.2% of the girls met criteria for DSM5 anorexia, bulimia, or binge eating disorder. When the researchers included nonspecific eating disorder symptoms, a total of 13.2% of the girls had suffered from a DSM-5 eating disorder by age 20.

Stice E, Marti CN, Shaw H, and Jaconis M. (2010). An 8-year longitudinal study of the natural history of threshold, subthreshold, and partial eating disorders from a community sample of adolescents. Journal of Abnormal Psychology, 118(3):587-97. doi: 10.1037/a0016481.

Young people between the ages of 15 and 24 with anorexia have ten times the risk of dying compared to their same-aged peers.

Smink, F. E., van Hoeken, D., & Hoek, H. W. (2012). Epidemiology of eating disorders: Incidence, prevalence and mortality rates. Current Psychiatry Reports, 14(4), 406-414.

Fichter, M. M., & Quadflieg, N. (2016). Mortality in eating disorders – Results of a large prospective clinical longitudinal study. International Journal of Eating Disorders, Epub ahead of print.

Males represent 25% of individuals with anorexia nervosa and are at a higher risk of dying.

Mond, J.M., Mitchison, D., & Hay, P. (2014) "Prevalence and implications of eating disordered behavior in men" in Cohn, L., Lemberg, R. (2014) Current Findings on Males with Eating Disorders. Philadelphia, PA: Routledge.

An ongoing study in Minnesota has found the incidence of anorexia increasing over the last 50 years only in females aged 15 to 24. Incidence remained stable in other age groups and in males.

Lai, K. Y. (2000). Anorexia nervosa in Chinese adolescents—does culture make a Lucas AR, Crowson CS, O'Fallon WM, Melton LJ 3rd. (1999). The ups and downs of anorexia nervosa. International Journal of Eating Disorders, 26(4):397-405. DOI: 10.1002/(SICI)1098108X(199912)26:4<397::AID-EAT5>3.0.CO;2-0.difference?. Journal of Adolescence, 23(5), 561-568.

Health Consequences

Credit to NEDA.

Cardiovascular System

  • When you don't consume enough calories, the body breaks down its tissue for fuel instead. The first tissue to be used is muscle tissue, including the heart. The more mass the heart loses, the more pulse and blood pressure drop. The cardiac muscle has less fuel and cells to pump blood, and the risk of heart failure increases.

  • The body will reduce its resting metabolic rate to conserve energy.

  • If the brain and blood vessels can't push enough blood to the brain, it can cause fainting or dizziness, primarily upon standing.

Gastrointestinal System

  • Anorexia can lead to slow digestion, known as gastroparesis. Food restriction interferes with regular 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

  • An AN patient can develop constipation, from any of the following:

  • Inadequate nutritional intake means the intestines don't have enough material for work properly.

  • 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

  • Both malnutrition and purging can cause pancreatitis, an inflammation of the pancreas. Symptoms include pain, nausea, and vomiting.


  • The brain consumes almost one-fifth of the body's daily calorie intake. Inadequate nutritional intake causes insufficient energy for the brain.

  • Extreme hunger at bedtime can create difficulties falling or staying asleep.

  • Neurons in all parts of the body require a protective layer of lipids for insulation; these lipids allow neurons to conduct electricity more efficiently. If the body doesn't have enough fat, it can damage this protective layer and cause numbness and tingling.

  • Severe dehydration and malnutrition can lead to electrolyte imbalances. Electrolytes are used by neurons to send electrical and chemical signals in the body. These imbalances can lead to seizures and muscle cramps.


  • Hormones are made from the fat and cholesterol we eat. Without the correct nutrients, levels of the following hormones can fall:

  • Sex hormones estrogen and testosterone

  • Thyroid hormones

  • Lowered sex hormones can

  • cause menstruation to fail to begin, to become irregular, or to stop completely.

  • 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.

  • 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 Consequences

  • 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.

Treatment Options

Credit to Healthline.

The first step to recovery is recognizing the problem. Treatment will work better when the patient accepts they have AN. The main point of treatment is to recover standard eating patterns and weight. Professionals recommended that the entire family participate in therapy; for some patients, AN is a lifelong battle.


Therapy options can be done in a one-on-one setting, with family, or in a group. The most common one-on-one option is Cognitive Behavioral Therapy (CBT). It helps the individual change thoughts and behavior; CBT helps the individual cope with emotions and self-esteem. The family therapy option is to resolve disputes. A therapist can help a family develop healthy eating habits along with a better understanding of anorexia. The last option is group therapy, where multiple individuals with AN meet to discuss their struggles. It is often lead by a medical professional.


There is currently no medication to treat anorexia nervosa. However, there is medication to address some of the underlying causes or co-existing mental health disorders that often accompany AN. These include depression and anxiety.


Hospitalization may be required if malnutrition and dehydration are extreme; when needed, a feeding tube or intravenous fluid may be administered. If an individual still refuses to eat, long-term hospitalization may be required.

Individuals might require more than one therapy option.

Book: Clinical Handbook of Complex and Atypical Eating Disorders

Author: Anderson, L.K.; Murray, S.B.; Kaye, W.H.

Publish Date: September 26, 2017

Price: $69 (Paperback)

Description: "Clinical Handbook of Complex and Atypical Eating Disorders brings together into one comprehensive resource what is known about an array of complicating factors for patients with ED, serving as an accessible introduction to each of the comorbidities and symptom presentations highlighted in the volume. The first section of the book focuses on the treatment of ED in the presence of various comorbidities, and the second section explores the treatment of ED with atypical symptom presentations. The third section focuses on how to adapt ED treatments for diverse populations typically neglected in controlled treatment trials: LGBT, pediatric, male, ethnically diverse, and older adult populations. Each chapter includes a review of clinical presentation, prevalence, treatment approaches, resources, conclusions, and future directions. Cutting edge and practical, Clinical Handbook of Complex and Atypical Eating Disorders will appeal to researchers and health professionals involved in treating ED."

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