Eating disorders are generally characterized by an obsessive preoccupation with weight and/or food that results in extreme disturbances in eating and other behaviors. These disorders are often chronic and dangerous because they can severely compromise a person’s health.

The three most common types of eating disorders include:

• Anorexia nervosa. This eating disorder is basically self-starvation.  To be diagnosed with anorexia nervosa, a person must weigh more than 15 percent below the normal range for their age and body size and exhibit a distorted body image, including a sometimes intense fear of gaining weight. People with anorexia nervosa usually lose weight by drastically reducing their food intake (fewer than 1,000 calories per day) and through excessive exercise (anorexia athletica). Among adolescents, anorexia may also be present when a person fails to gain age-appropriate weight during puberty and post-puberty, even if he or she is not losing much weight. According to the U.S. Department of Health and Human Services, it ranks as the third most common chronic illness among adolescent girls in the nation.
  
  Anorexia nervosa has severe, life-threatening complications. Prolonged starvation can lead to malnutrition and damage of the vital organs, including the heart and brain. In addition, nutritional deprivation often results in the loss of bone mass (osteoporosis), which may result in brittle bones that break easily. Other complications include amenorrhea (loss of menstrual periods), anemia (low red blood cell count), hair loss, infertility (inability to get pregnant) and a failure to grow to normal stature in children or adolescents. If left untreated, patients with anorexia nervosa may literally starve themselves to death.
  
  
• Bulimia nervosa. Also called bulimia or binge-purge syndrome, this eating disorder is characterized by a pattern of binge eating followed by harmful behaviors to control or prevent any resulting weight gain. Binge eating is defined as the consumption of excessive amounts of food in a short time period. The food is often high in calories and easy to consume (e.g., ice cream). Typically, people with bulimia purge themselves of eaten food by either self-induced vomiting or the use of laxatives (usually mild drugs for stimulating bowel movement), diuretics or, rarely, enemas (injecting liquid into the intestines through the anus to empty the bowels). To be diagnosed with bulimia, these types of behaviors must have occurred on average a minimum of two times a week for three months.
  
  Patients with bulimia may cause harm to their bodies with frequent episodes of binging and purging. Complications of bulimia include electrolyte imbalance (a loss of vitamins and minerals that are crucial for normal organ functioning, such as potassium) and dehydration (loss of water), which may lead to weakness and irregular heart rhythms. Other complications include tooth and gum decay caused by the acids contained in the vomit, digestive problems (e.g., constipation) and medication abuse (e.g., diuretics, stimulants, diet pills). In prolonged or severe cases, binge eating may cause the stomach to rupture and chronic purging may result in heart failure.
  
  
• Binge eating disorder (BED). This disorder, which is a research diagnosis is not yet fully accepted, is mainly identified by recurring episodes of uncontrolled, rapid eating, often followed by remorse and guilt. The binging or overeating typically does not stop until the person is uncomfortably full, and the person usually eats alone because of embarrassment. BED differs from anorexia nervosa and bulimia nervosa in that it is not associated with purging behaviors (e.g., self-induced vomiting, use of laxatives) to avoid the weight gain. However, individuals with this type of eating disorder sometimes may engage in chronic dieting attempts and/or fasting. Also, BED may sometimes be difficult to differentiate from overweight or obesity. Individuals with BED often feel out of control when it comes to their binges and have accompanying feelings of depression, guilt and self-disgust.
  
  Complications of binge eating disorder include obesity, high blood pressure, high cholesterol levels, heart disease, type 2 diabetes (uncontrolled blood sugar) and gallbladder disease (inflammation or infection of the sac gallbladder, which helps digest fats).

Other less common types of eating disorders include:

• Pica. This eating disorder involves the chronic craving and consumption of nonfood items including dirt, clay, paint chips, chalk, cornstarch, baking soda, coffee grounds, cigarette ashes or butts, burnt match heads, feces, ice, glue, hair, buttons, paper, sand, toothpaste and soap. Pica occurs more often in people with developmental disabilities (e.g., autism, mental retardation), children between the ages of 2 and 3 years and, sometimes, pregnant women. Even though infants younger than 18 months to 24 months may try to eat nonfood items, it is generally not considered abnormal at that age. In most cases, toddlers spontaneously outgrow the disorder and, in pregnant women, pica usually resolves after giving birth.
  
  Complications of pica may include lead poisoning (from eating paint chips in older buildings with lead-based paint), bowel problems, intestinal obstruction or perforation, dental injury, parasitic infections and malnutrition. Sometimes, this eating disorder may be life-threatening if a patient consumes a toxic or lethal substance. Also, pregnant women with the disorder may cause harm to their fetus if they consume harmful substances.
  
  
• Rumination disorder. An eating disorder characterized by the repeated regurgitation (throwing up) and re-chewing of partially digested food, which is then re-swallowed or expelled. In rumination, regurgitation appears effortless and may be preceded by a belching sensation and usually does not involve nausea or vomiting. This disorder is more common in infants and individuals with severe and profound mental retardation. However, it generally resolves itself spontaneously in healthy infants with the disorder.
  
  Complications of rumination include dehydration and electrolyte imbalance, gastric problems, upper respiratory distress, dental problems (e.g., tooth decay), aspiration (deviation of food into the lungs), choking, pneumonia (inflammation of the lungs) and malnutrition.

In addition, some patients may have an eating disorder that does not fit the criteria for any of the recognized eating disorders. In such cases, a diagnosis known as “eating disorder not otherwise specified” (EDNOS) may be made. In EDNOS, individuals engage in some form of abnormal eating behavior but do not exhibit all the specific symptoms required to diagnose an eating disorder. For instance, a female with EDNOS may meet all the criteria of anorexia nervosa but despite the significant weight loss, she manages to maintain a normal weight or has regular menstrual periods.