Given the current epidemic of obesity, you hear a lot about the importance of avoiding overeating. But you probably don't hear nearly as much about people who have access to food but struggle with undereating. Yet, for millions of people with anorexia nervosa or other eating disorders, an unhealthy loss of weight is the major challenge. It can be difficult for those with normal diets to understand how these conditions develop. Indeed, there is much we don't understand about these conditions.
What are eating disorders?
Eating disorders are a group of conditions marked by abnormal eating habits that reduce the quality of a person's physical or mental health. They tend to occur more commonly among women than men.
These conditions include:
- anorexia nervosa
- avoidant/restrictive food intake disorder
- binge eating disorder
- bulimia nervosa
- rumination disorder.
Specific criteria have been developed by the American Psychiatric Association to diagnose each of these. For example, the criteria for anorexia nervosa include:
- significant limitation of nutritional intake leading to a much lower body weight than expected.
- an excessive fear of being fat or putting on weight, or behavior that hinders weight gain despite having a low body weight.
- an abnormality of how body weight or shape is experienced, a preoccupation with self-evaluation based on body weight or shape, or consistent lack of insight into how serious low body weight is.
In the case of anorexia nervosa, there is also a description of whether the condition is the restricting type (in which weight loss has developed primarily by fasting, dieting, or exercise) or the binge eating/purging type (in which the person repeatedly binge eats and purges by self-induced vomiting or abuse of laxatives, enemas, or diuretics).
Some of the most common symptoms are due to low body mass, including:
- amenorrhea (a loss of menstrual periods in women)
- feeling cold and having cool extremities
- dizziness or feeling faint
- loss of muscle mass
- lack of growth or development (in adolescents)
- constipation or diarrhea
- trouble thinking, seizures or abnormal sensations in the extremities
- dry skin with fine, dark hair.
Serious medical problems, such as an abnormal heart rhythm, may cause fainting or even sudden death.
Other symptoms vary depending on the type of eating disorder. The symptoms of anorexia nervosa are described in the criteria listed above. Symptoms of the other eating disorders are as follows:
- Avoidant/restrictive food intake disorder — With this condition, people avoid food due to a sensation of choking or other negative experience, lack of appetite or interest in food and no other medical or psychological explanation for these symptoms.
- Binge eating disorder — People with this type of eating disorder regularly eat unusually large amounts of food while feeling a lack of control or inability to stop eating. Typically, food is eaten rapidly with an uncomfortable feeling of fullness. Binging may occur despite not being hungry; embarrassment about one's eating habits (leading to eating alone), and feelings of disgust, guilt, or depression are common.
- Bulimia nervosa — The typical person with bulimia nervosa has an excessive focus on weight and body shape, regularly binge eats and then takes unusual measures to avoid weight gain, including abuse of laxatives, diuretics, or other medications, self-induced vomiting, exercise or fasting.
- Pica — People with this condition repeatedly crave and eat dirt, clay, chalk, or other inedible things. It's more common among those who are pregnant, or have iron deficiency, an intellectual disability, or another psychiatric disorder such as schizophrenia.
- Rumination disorder — Symptoms include persistent episodes of vomiting up food that is then chewed again, swallowed, or spit out. This occurs despite an evaluation that reveals no medical explanation.
In general, the cause (or causes) of eating disorders is unknown. Research suggests that contributors may include:
- environmental factors, such as a culture that glorifies and ties self-worth to thinness
- a genetic tendency
- altered brain function or structure.
Ideally, people with eating disorders are cared for by a team of health professionals, including a mental health expert, nutritionist, and primary care physician. The mainstays of therapy include nutritional support and psychotherapy. Medications, such as olanzapine, may be recommended as well. Admission to a psychiatric facility may help decelerate or stop weight loss and hasten recovery. Medical complications, such as abnormal heart rhythm or dangerously abnormal electrolyte levels, may require hospital admission.
The prognosis of the various eating disorders varies widely as does severity, duration, and response to treatment. Some adolescents have a relatively brief course of illness without difficulties in adulthood while for others challenges with healthy eating is lifelong or even fatal.
The bottom line
It's a common misconception that eating disorders are an intentional effort to look good or get attention. The truth is that they are a group of poorly understood and potentially dangerous conditions that may be due to genetic influences or abnormal brain function. Prompt diagnosis and treatment are essential. There is a pressing need for more research to better understand these disorders and to come up with better treatments.
— Robert H. Shmerling, MD
Robert H. Shmerling, MD, is associate professor of medicine at Harvard Medical School and Clinical Chief of Rheumatology at Beth Israel Deaconess Medical Center in Boston where he teaches in the Internal Medicine Residency Program. He is also the program director of the Rheumatology Fellowship. He has been a practicing rheumatologist for over 25 years.
To learn about the latest and most effective treatment approaches, including cognitive behavioral therapies, psychotherapy, and medications, buy the Harvard Special Health Report Coping with Anxiety and Stress Disorders.