While nearly two out of three U.S. adults struggle with issues related to being overweight, a smaller but significant portion of the population has eating disorders that typically result in being normal weight or underweight. Often, individuals are fearful of gaining weight. Individuals who suffer from bulimia nervosa and anorexia nervosa face many adverse health consequences (Mayo Clinic, 2012a, 2012b).

Anorexia nervosa (AN) is an eating disorder characterized by the maintenance of a bodyweight well below average through starvation and/or excessive exercise. Individuals suffering from anorexia nervosa often have a distorted body image, referenced in literature as a type of body dysmorphia, meaning that they view themselves as overweight even though they are not.

Signs and Symptoms

Figure 1. While being physically active is healthy, excessive exercise may be indicative of a serious issue.

People with anorexia nervosa may see themselves as overweight, even when they are dangerously underweight. People with anorexia nervosa typically weigh themselves repeatedly, severely restrict the amount of food they eat, often exercise excessively, and/or may force themselves to vomit or use laxatives to lose weight. Anorexia nervosa has the highest mortality rate of any mental disorder. While many people with this disorder die from complications associated with starvation, others die of suicide.

Symptoms include the following:

• extremely restricted eating
• extreme thinness (emaciation)
• a relentless pursuit of thinness and unwillingness to maintain a normal or healthy weight
• intense fear of gaining weight
• distorted body image, a self-esteem that is heavily influenced by perceptions of body weight and shape, or a denial of the seriousness of low body weight

The DSM-5 criteria for anorexia categorizes the ways people attempt to lose weight into two subtypes: restrictive and binge-eating/purging. In addition, both subtypes will also sometimes engage in excessive exercise in an effort to lose weight. A patient can be diagnosed with anorexia when they have a bodyweight that is less than 85% of normal BMI in conjunction with fear and preoccupation with gaining weight and a distorted body image and perception despite being underweight.^[1]

Other symptoms may develop over time, such as:

• thinning of the bones (osteopenia or osteoporosis)
• mild anemia and muscle wasting and weakness
• brittle hair and nails
• dry and yellowish skin
• growth of fine hair all over the body (lanugo)
• severe constipation
• low blood pressure slowed breathing and pulse
• damage to the structure and function of the heart
• difficulty concentrating
• brain damage
• multiorgan failure
• drop in internal body temperature, causing a person to feel cold all the time
• lethargy, sluggishness, or feeling tired all the time
• amenorrhea
• infertility

Etiology

Estimations are that between 0.3%–2% of young women and 0.1%–0.3 % of males will develop anorexia. Anorexia is a serious disease, especially given that people with anorexia aged 15 to 24 have 10 times the risk of dying compared to their similar-age peers. Furthermore, male individuals with anorexia are at even higher risk of dying due to late diagnosis as a result of sociocultural influences than males do not have eating disorders.^[2]

Genetic

Anorexia nervosa is highly heritable. Twin studies have shown a heritability rate of between 28%–58%, with many studies estimating the heritability of the disorder in the higher range, above 50%.^[3] First-degree relatives of those with anorexia have roughly 12 times the risk of developing anorexia. Some studies have shown some associations between anorexia and 43 different genes that are connected to regulating eating behavior, motivation, reward mechanics, personality, and emotion. Epigenetic modifications, such as DNA methylation, may contribute to the development or maintenance of anorexia nervosa, though clinical research in this area is in its infancy.

A 2019 study found a genetic relationship between anorexia and other mental disorders, such as schizophrenia, obsessive-compulsive disorder, anxiety disorders and depression. An important find in the research is that there appears to be a a link between anorexia and metabolic funcitoning—the research found significant negative correlations between anorexia and fat mass, BMI, obesity, type 2 diabetes, insulin resistance, and fasting insulin.^[4]

Environmental

Obstetric complications, prenatal and perinatal issues, may factor into the development of anorexia nervosa, such as preterm birth, maternal anemia, diabetes mellitus, preeclampsia, placental infarction, and neonatal heart abnormalities. Neonatal complications may also have an influence on harm avoidance, one of the personality traits associated with the development of anorexia nervosa.

Neuroendocrine dysregulation, or altered signaling of peptides that facilitate communication between the gut, brain, and adipose tissue, such as ghrelin, leptin, neuropeptide Y, and orexin, may contribute to the pathogenesis of anorexia nervosa by disrupting the regulation of hunger and satiety.

Figure 2. Those with celiac disease can’t consume foods like bread because they contain gluten.

People with gastrointestinal disorders may be more at risk of developing disorders of eating practices than the general population, principally restrictive eating disturbances. An association of anorexia nervosa with celiac disease has been found. The role that gastrointestinal symptoms play in the development of eating disorders seems rather complex. Some authors report that unresolved symptoms prior to gastrointestinal disease diagnosis may create a food aversion in these persons, causing alterations to their eating patterns. Other authors report that greater symptoms throughout their diagnosis led to greater risk. Some people with celiac disease, irritable bowel syndrome, or inflammatory bowel disease who are not conscious about the importance of strictly following their diet choose to consume their trigger foods to promote weight loss. On the other hand, individuals with good dietary management may develop anxiety, food aversion, and eating disorders because of concerns around cross-contamination of their foods. Some authors suggest that medical professionals should evaluate the presence of unrecognized celiac disease in all people with an eating disorder, especially if they present any gastrointestinal symptom (such as decreased appetite, abdominal pain, bloating, distension, vomiting, diarrhea, or constipation), weight loss, or growth failure; and also routinely ask celiac patients about weight or body shape concerns, dieting or vomiting for weight control, to evaluate the possible presence of eating disorders, especially in women.

Studies have hypothesized the continuance of disordered eating patterns may be epiphenomena of starvation. The results of the Minnesota Starvation Experiment showed normal controls exhibit many of the behavioral patterns of anorexia nervosa when subjected to starvation. This may be due to the numerous changes in the neuroendocrine system, which results in a self-perpetuating cycle.

Anorexia nervosa is more likely to occur during puberty. Some explanatory hypotheses for the rising prevalence of eating disorders in adolescence are “increase of adipose tissue in girls, hormonal changes of puberty, societal expectations of increased independence and autonomy that are particularly difficult for anorexic adolescents to meet; [and] increased influence of the peer group and its values.”^[5]

Psychological

Early theories of the cause of anorexia linked it to childhood sexual abuse or dysfunctional families; the evidence is conflicting, and well-designed research is needed. The fear of food is known as sitiophobia, cibophobia, and is part of the differential diagnosis. Other psychological causes of anorexia include low self-esteem, feeling like there is a lack of control, depression, anxiety, and loneliness.

Sociological

Anorexia nervosa has been increasingly diagnosed since 1950; the increase has been linked to vulnerability and internalization of body ideals. People in professions where there is a particular social pressure to be thin (such as models and dancers) were more likely to develop anorexia, and those with anorexia have much higher contact with cultural sources that promote weight loss. Anorexia can also be observed for people who partake in certain sports, such as jockeys and wrestlers. There is a higher incidence and prevalence of anorexia nervosa in sports with an emphasis on aesthetics, where low body fat is advantageous, and sports in which one has to make weight for competition. Family group dynamics can play a role in the cause of anorexia. When there is constant pressure from people to be thin, teasing, and bullying can cause low self-esteem and other psychological symptoms.

Media effects

Figure 3. Young women in our society are inundated with images of extremely thin models (sometimes accurately depicted and sometimes digitally altered to make them look even thinner). These images may contribute to eating disorders. (credit: Peter Duhon)

Persistent exposure to media that presents body ideals may constitute a risk factor for body dissatisfaction and anorexia nervosa. The cultural ideal for body shape for men versus women continues to favor slender women and athletic, V-shaped muscular men. A 2002 review found that, of the magazines most popular among people aged 18 to 24 years, those read by men, unlike those read by women, were more likely to feature ads and articles on shape than on diet. Body dissatisfaction and internalization of body ideals are risk factors for anorexia nervosa that threaten the health of both male and female populations.

Websites that stress the importance of attainment of body ideals extol and promote anorexia nervosa through the use of religious metaphors, lifestyle descriptions, and “thinspiration” or “fitspiration” (inspirational photo galleries and quotes that aim to serve as motivators for the attainment of body ideals). Pro-anorexia websites reinforce the internalization of body ideals and the importance of their attainment.

The media portray a false view of what people truly look like. In magazines and movies and even on billboards, most of the actors/models are digitally altered in multiple ways. People then strive to look like these “perfect” role models when in reality they are not near perfection themselves

While both anorexia and bulimia nervosa occur in men and women of many different cultures, Caucasian females from Western societies tend to be the most at-risk population. Recent research indicates that females between the ages of 15 and 19 are most at risk, and it has long been suspected that these eating disorders are culturally bound phenomena that are related to messages of a thin ideal often portrayed in popular media and the fashion world (Smink et al., 2012). While social factors play an important role in the development of eating disorders, there is also evidence that genetic factors may predispose people to these disorders (Collier & Treasure, 2004).

Treatment

Patients with anorexia nervosa require and benefit from a multidisciplinary approach to treatment, involving nutritional support, psychological counseling, and behavioral modification. The aggressiveness of treatment can be determined by their health stability including a patient’s weight and age. If an adult patient has lost 15% of their set point bodyweight it is recommended that they participate in inpatient treatment or a highly structured outpatient program. However, it is recommended for children and adolescents to do inpatient in combination with family therapy before the 15% weight-loss threshold to avoid developmental risks and damage.^[6]

Nutritional therapy to promote weight gain

Patients with anorexia often suffer from severe malnutrition, which causes them to have a more negative, obsessive, and manipulative mindset. When a person with anorexia enters treatment, it is important to keep their mentality in perspective and coordinate a treatment plan that meets the patient at their current health status and be sympathetic, rather than punitive, in manner. A first step is to promote weight gain—often an estimated amount of two to three pounds per week during inpatient care and one pound per week in outpatient settings.

Medication options

Although medications are often prescribed for patients with anorexia nervosa, there is limited evidence to support their effectiveness—either at promoting weight gain or at alleviating psychological distress. There are two general types of medications prescribed: antidepressants and antipsychotics.

Psychotherapy to foster recovery and prevent relapse

Once patients gain enough weight to benefit from psychotherapy and behavioral interventions, the goal of treatment shifts from medical stabilization and gaining weight to learning how to recognize their distorted thinking about food and develop coping strategies to deal with their emotions and stress to avoid relapse. Estimations of relapse within one year of being discharged is approximately 50% of patients who recover in inpatient programs.^[8]