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Health Topics A-Z
Health Topics by Category
Health Topics for Eating Disorders
Metabolism
UI Behavorial Health
Department of Psychiatry
Eating Disorders Program
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Eating and Weight Disorders
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- Abnormal eating behaviors are typically caused by a combination of factors, including social norms promoting thinness, personality vulnerabilities, distortions of perceived appearance, overvaluing the benefits of weight or shape change, and dieting itself, especially at critical stages of development. Together, these forces can lead to critical stages of development. Together, these forces can lead to self-sustaining eating disorders, primarily anorexia nervosa and bulimia nervosa. Abnormal eating behaviors that begin as a response to calorie restriction gradually become coping mechanisms for problems in self-esteem, interpersonal relationships, and mood regulation. These behaviors are sustained by a determined pursuit of thinness and an irrational fear of fatness as well as distortion of body image.
Physicians must be able to recognize eating disorders and understand their potential complications, which can include death from severe malnutrition, electrolyte abnormalities and suicide in depressed patients. The earlier an eating disorder is diagnosed, the better the patient will do. The first clue to anorexia or bulimia nervosa may be subtle. For example, women may present with amenorrhea caused by weight loss, with fractures from estrogen deficiency-related osteoporosis, or with esophagitis or loss of tooth enamel from repeated vomiting. When patients with eating disorders present with weight loss, the physician must consider other disorders such as hyperthyroidism, diabetes mellitus, malabsorption, and malignancy. However, the excessive and unrealistic fear of fatness in patients with anorexia nervosa differentiates it from other psychiatric and medical conditions causing weight loss.
Overweight is a risk factor for many important disorders, including hypertension, hypercholesterolemia, diabetes mellitus, and, in women, endometrial carcinoma. Morbid obesity, a weight greater than twice normal, can lead to potentially fatal cardiopulmonary disease. Obesity is typically multifactorial. In addition to excessive eating, common contributing factors are genetic predisposition, social class norms, nutrient availability and density, basal and exercise-dependent energy expenditure, and, occasionally, underlying medical, neurologic, or psychiatric disorders. In general, the more severe the weight abnormality and the earlier it manifests, the more likely genetic or medical factors are involved. Binge-eating disorder is present in approximately 25% of obese individuals.
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- The search for freedom from starvation has characterized much of human history; paradoxically, the availability of plentiful food in modern industrialized cultures can provoke extreme reactions. Especially since the 1950's, western industrialized nations have increasingly defined attractiveness in terms of artificial norms for thinness. In the United States, adult weight in both sexes decreases as social class increases. About 75% of American women feel fat, but only about 25% are overweight. Although men have been less severely afflicted by the drive for thinness, they, too, have been increasingly preoccupied with changing their body shape.
Reported cases of anorexia and bulimia nervosa for Canada, U.S. and Europe including U.K. have increased severalfold in recent decades, through both actual higher incidences and more accurate diagnosis. An estimated 0.51% to 1% of young women in Western societies suffer from the full syndrome of anorexia nervosa, to 2-4% of American college women meet the criteria for bulimia nervosa, and up to 5% of young Westernized women of college age suffer from atypical or partial syndromes. Six times as many women as men are affected. A much larger percentage of Americans (more than 50%) are restrained eaters (interrupting eating behavior before normal comfortable satiety terminates a meal) in other words, the foot is always on the brake while eating or chronic dieters.
The body normally regulates nutrient intake with exquisite sensitivity around a "set point" that maintains weight within a narrow range which remains stable or changes slowly over time. When not afflicted by medical or psychological disorders or by coercive sociocultural norms, people who choose to eat primarily foods low in fats and concentrated sweets, who exercise regularly, and who deal reasonably with everyday stresses, tend to stay within a narrow and usually normal weight range. A role for genetic factors in defining this weight range is supported by twin and adoption studies. However, these built in stable patterns of "motivated behavior" are subject to many aberrations in the United States, more often from learned sociocultural norms than from medical or psychiatric diseases.
Eating disorders can be diagnosed by relatively specific symptoms and signs. Although the fundamental causes of eating disorders are unknown, these conditions can be more accurately identified than many medical disorders for which laboratory tests exist.
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- The diagnostic criteria for anorexia nervosa are: 1.) self-induced starvation to a weight at least 15% below normal; 2.) an intense, irrational fear of becoming fat; and 3) hypogonadism, manifested in women by missing three consecutive menstrual periods, and in men by a decrease in sexual function and interest. Although the disorder is termed "anorexia," patients lose their appetite only after losing considerable weight. Another feature seen in many patients, though not a criterion for diagnosis, is a distortion of perception in which patients believe that they are fatter than they really are.
In more than 95% of patients, anorexia nervosa begins with a conscious wish to lose weight through dieting, often combined with exercise, and occasionally augmented by self-induced vomiting and abuse of laxatives, diuretics, or diet pills. The disorder generally takes root after months or years of self-critical scrutiny of body size and shape. Some patients begin dieting because their friends or family members are dieting or are making comments about the patient's appearance. The peaks of onset of primary anorexia nervosa are the early and late teens, (14 and 18 years of age). Onset is possible as early as age seven and as late as the 70's. Persons especially predisposed are young women with sensitive, self-critical, and sometimes compulsive aspects to their personality, who come from families with a history of depressive disorder as well as an "enmeshed" (living in each other's pockets without freedom to grow separately; having excessive reactivity to each others moods and behaviors" style of family functioning. Participation in sports, ballet, modeling, wrestling, and other activities that promote thinness accentuates the drive to lose weight.
Anorexic individuals usually come to medical attention because of concern by family, friends, teachers, and sometimes coaches, rather than because the patients themselves are worried. Anorexia nervosa, although often concealed by layers of clothing, is a relatively public disorder. Driving their weight loss is the excessive and unrealistic fear of fatness, a symptom clearly differentiating anorexia nervosa from other psychiatric and medical causes of weight loss.
Two major classes of patients with anorexia nervosa have been identified: those who solely restrict their food intake (restricting subtype), and those who binge while at low weight, and then induce vomiting or abuse laxatives or diuretics (binge/purge subtype). Patients with both subtypes organize their behaviors, social lives, thinking, and ultimately their identity around promoting and maintaining weight loss and resisting weight gain. Families are distressed by the anorexic behavior, which resists both entreaties and threats. This usually makes families feel helpless, angry, or defeated, and occasionally provokes abuse.
The final, chronic stage of the disorder has two features. The illness becomes autonomous, resisting change, and the patient develops an identity based on the anorexia nervosa, a "sick role" that derails normal social and psychological development. The chronically low weight may also be sustained by the pathophysiologic effects of malnutrition, such as slowed gastric emptying and severe abdominal distress.
Patients' emaciated state has characteristic signs, including hypotension, bradycardia, decreased core temperature, and loss of both intra-abdominal and subcutaneous body fat as well as decreased muscle mass. Radiographic and laboratory studies may reveal osteoporosis, brain shrinking, and variable degrees of anemia and endocrine dysfunction. Gonadotropins and sex steroid concentrations are low, as can be the serum T3 but thyroxine is usually normal. Circulating cortisol and growth hormone concentrations are often high.
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Most patients meeting the full criteria for anorexia nervosa need to be treated as inpatients for several weeks to months. Patients are first stabilized medically, and then started on nutritional rehabilitation. The best approach to feeding is persuading patients to accept healthy amounts of food, prescribed as medicine, with the promise that they will not be allowed to become fat. Nasogastric tubes are rarely necessary, and parenteral hyperalimentation is fraught with potential complications. Feeding may cause abdominal distress as well as mild peripheral edema, which responds to elevation of the feet; rarely, the stomach dilates. Education and support help patients understand their illness and need for treatment.
Nutritional rehabilitation is only the prelude to definitive management. The central challenge is persuading patients to think differently about their body size and nutritional needs, and to appreciate the role that their illness has come to serve in their life. Management is also directed toward identifying and treating coexisting mood, anxiety, and personality disorders, and alcohol or other substance abuse. After the patient's weight has been restored to a healthy range, intensive practice in patterns of healthy daily living consolidates the treatment gains. Treatment of individuals under 18 year old seldom succeeds unless it includes the whole family. Aftercare usually requires two to three years, and may involve individual, group, or family treatment.
The death rate from anorexia nervosa is as high as 18%, primarily from medical complications and suicide. Most patients who survive eventually improve, but improvement occurs over a broadly disparate time frame from years to decades later. Coexisting psychiatric conditions, especially mood disorders, personality disorders, and substance abuse, often prove to be the most difficult aspects of long-term treatment. Mortality can be reduced by prompt medical stabilization of low weight and hypokalemia, and by recognition and treatment of co-occurring depressive illness (30-50% of cases). The good news is that with effective treatment (acute plus relapse prevention), the disorder is curable, not merely subject to improvement.
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- "Bulimia," derived from the Greek words for "ox" and "hunger," is a syndrome that includes two elements: 1) binge eating and 2) self-induced vomiting, laxative abuse, or other measures to avoid weight gain . A specific criterion for bulimia is repeated episodes of binge eating (an average of twice a week for 3 months), during which patients feel that they cannot control their eating. Purging is not essential to the diagnosis, but occurs in 80% of cases. The term "nervosa" was recently added to "bulimia" to emphasize the features that it shares with anorexia nervosa, primarily the relentless pursuit of lower weight and the morbid fear of fatness. Patients with bulimia may be over, under, or at ideal body weight, with normal weight range most common. A diagnosis of anorexia nervosa takes precedence over bulimia if weight is below 85% of normal.
Like anorexia nervosa, bulimia nervosa usually begins by dieting. Dieters tend toward bulimia rather than anorexia when their hunger overcomes their attempt to restrict food and they begin binge eating, which is not in itself abnormal in food deprivation when faced with abundant nutrition. The clinical disorder emerges when a morbid fear of fatness entrenches itself, and patients suffer psychological distress or medical complications after binge eating and subsequent purging and especially when binges are provoked by emotional distress rather than hunger.
Bingeing is promoted by restricting food early in the day (no breakfast, salad for lunch), so an appetite builds that may not express itself until late afternoon or evening, the most common times for bingeing. In extreme cases, patients consume 10,000 to 30,000 calories a day and binge throughout the day. The patient's social life becomes organized around secret binge and purge episodes, requiring carefully timed entrances and exits. In a substantial minority of patients, bulimic behavior is part of a broader pattern of abnormally impulsive behavior, including alcohol or other drug abuse, sexual promiscuity, and stealing.
Patients can develop bulimia at any age from the preteens to the 50's with the peak onset of few years later than anorexia nervosa, 18-20 year old. Half of patients have a history of anorexia nervosa or an anorexia-like episode. Bulimia may alternate with anorexia nervosa in an irregular sequence over several decades.
Bulimia has diverse complications. Nonspecific abnormalities of gastric emptying and bowel function can cause abdominal distention that may worsen patients' distorted perception of their body size and increase their desire to purge. Repeated regurgitation of gastric secretions erodes the enamel on the lingual surfaces of teeth. Serious complications include systemic hypokalemic alkalosis, leading to cardiac arrhythmias, renal damage, and seizures. If patients use the emetic Ipecac, the emetine that it contains can cause myocardial damage similar to viral myocarditis. Most deaths among patients with bulimia are caused by arrhythmias or suicide.
Even after psychological treatment has succeeded in stopping their binge/purge behavior, patients may have persistent esophageal reflux that provokes unwanted vomiting for years.
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After diagnosis and initial medical assessment, many patients with bulimia nervosa can be treated as outpatients, with a goal of gradually decreasing the frequency and severity of their bingeing and purging. But some patients must have their behavior interrupted abruptly by hospitalization, especially if severe and intractable or accompanied by suicide plans or medical complications. Bulimia sufferers are usually surprised and relieved to find that eating moderate quantities of food three times a day does not make them fat, as they had feared.
After bingeing and purging is stopped and any medical complications are treated, the focus of management turns to long-term inhibition of binge/purge behavior with cognitive-behavioral therapy. As in management of anorexia nervosa, the physician must recognize the commonly coexisting psychiatric conditions. About 50% of bulimic patients benefit from an antidepressant drug. Regular moderate exercise is helpful in both managing stress and promoting a healthy body shape and composition. Both cognitive behavioral psychotherapy, and interpersonal psychotherapy, have been shown to produce significant enduring improvements, greater than antidepressants alone. The disorder has a good outcome if treated vigorously.
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- Eating disorders in some patients may not fulfill all the criteria for anorexia nervosa or bulimia. For example, patients may have lost less than 15% of body weight or have fewer than two binge-purge episodes per week for 3 months, but have other typical, albeit milder, features of the disorders. These are called atypical eating disorders. Binge-eating disorders (binges with no compensation) is a common "atypical" eating disorder.
Eating disorders can be manifestations or secondary complications of other medical and psychiatric conditions. For example, major depressive illness frequently causes substantial weight loss. Schizophrenia may lead to weight loss in individuals deluded by suspicions of poisoned food. Patients with dementia syndromes such as Alzheimer's disease have progressive cognitive incapacity that may prevent them from eating enough. Patients with panic disorder who develop social phobias about eating or vomiting in public may avoid food.
A number of medical conditions cause weight loss, including a few in which patients actually increase their caloric intake, e.g., hyperthyroidism, insulin-dependent (type I) diabetes mellitus, malabsorption, tuberculosis, and intestinal parasites. Tumors of the hypothalamus can cause appetite to decrease or increase. Decreased consciousness, cocaine or amphetamine abuse, and many drugs can all cause people to lose weight. But in contrast to patients with anorexia nervosa, people with weight disorders caused by these other conditions usually perceive themselves to be too thin and manifest no phobic fear of fatness.
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- In some people, obesity appears to be a genetically programmed trait. These individuals typically become progressively and severely overweight even before adolescence, and have a family history of extreme obesity. The pathophysiology in these patients, and the role that genetic factors play in more common and milder forms of obesity that develop later in life, are readily inferred but still poorly understood. When both parents are obese, a child has a 90% chance of being overweight; when one parent is obese, a 40% chance; and when neither parent is obese, only a 10% chance. A few syndromes of congenital hypothalamic hyperphagia have been described, e.g., the Prader Willi syndrome, in which young children develop severe obesity, hypogonadism, and some degree of mental retardation.
Most often, mild to moderate obesity is acquired later in life. In addition to a genetic predisposition, this common form of overweight is attributable principally to a "good life" of ample, dense calories, with infrequent exercise and poor stress management.
The essential first step in treating patients with routine mild to moderate adult-onset obesity is to approach it nonjudgmentally, appreciate its multifaceted pathogenesis, and consider critically whether the patient really needs to lose any weight, or more likely to exercise more and consume fewer fats. Unless the extra weight is causing or exacerbating diabetes mellitus, hyperlipidemia, or hypertension, it is not clear that mildly to moderately obese people need to lose weight. Some authorities have demonstrated that repeated cycles of weight loss and gain may promote cardiovascular illness as much as or even more than simply remaining at a mildly elevated but stable weight.
The only ways proven to treat mild to moderate obesity effectively and safely over the long term are those in which patients change their eating habits by lowering the caloric density of their food, and get more exercise. Courses of virtually all appetite-suppressing drugs, whether prescribed or over-the-counter (most of the latter contain phenylpropanolamine or caffeine), are followed by a weight rebound. Furthermore, many of these compounds can cause significant medical or psychiatric complications. Similarly, thyroid hormone preparations have no demonstrated long-term efficacy but substantial risks, especially for patients with heart disease. Particularly when a patient is motivated, e.g., by a diagnosis of hypertension or by early disease or death in obese relatives, the physician may be able to institute effective and sustainable diet and exercise changes.
Patients with morbid obesity (more than twice desirable weight) can suffer life-threatening consequences such as cardiopulmonary failure. For these patients, more aggressive approaches can sometimes be justified. Unfortunately, behavioral techniques alone seldom work. Gastric surgery with stapling to reduce stomach size has supplanted previous intestinal bypass procedures, which led to frequent complications in as many as 50% of patients. Gastric stapling is often successful for morbid obesity - a serious procedure but with fewer complications.
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- Prudent clinicians do not push overweight patients to lose weight unless they have evidence of health risks. Percent of body fat, which can be estimated based on skinfold thickness and distribution of fat rather than weight, may be more critical factors in determining medical risk than weight alone. Risk may increase when body fat exceeds 26-28% in women and men.
Distribution of body fat is also important. Concentration of fat in the abdomen in men, and in the upper torso especially around the shoulders in women, is linked to earlier onset of coronary artery disease and noninsulin-dependent (type II) diabetes mellitus. For example, risk for cardiovascular disease increases when the ratio of waist circumference to hip circumference exceeds 0.95 in men and 0.80 in women. However, little is known about what hormonal and other factors determine body fat distribution, how to alter it, and how much the associated cardiovascular risks can be reversed. While recent enthusiasns have surfaced for using growth hormone or testosterone in men in their 50's - 70's to decrease fat, and to increase muscle mass, conclusive studies of enduring risks and benefits are not completed. Although women may not like a gynoid ("pear") distribution of weight, it is safer in the long run than the android ("apple") distribution. Exercise has been demonstrated in convincing studies to be an independent health -promoting factor, especially in formally sedentary people who now regularly maintain about 4-6 hours of moderate exercise per week. For those people with a BMI of 26-30 (19-25 is normal), becoming fitter (↑ lean muscle mass and exercise capacity) appears to be as important as losing weight
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- Body weight is normally determined by poorly understood genetic factors, calories consumed, and energy expended basally and with exercise.
The key feature of the major eating disorders, anorexia and bulimia nervosa, is a phobic fear of fatness that leads to self-induced starvation or bingeing and purging. Typically begun as dieting spurred by social norms and personal vulnerabilities, the conditions can become self-sustaining and life-threatening.
Eating disorders can cause such diverse problems as amenorrhea, esophagitis, irritable bowel syndrome, and osteopenia.
Weight loss secondary to other conditions can be distinguished from primary eating disorders by patients' recognition that they are too thin.
Morbid obesity increases cardiopulmonary mortality, justifying aggressive behavioral and even surgical intervention. Mildly to moderately overweight patients may need treatment only if their weight is causing or worsening other medical conditions, and are generally benefited by increased physical actively and decreased fat consumption without the chronic hunger of dieting. Generally dieting is ineffective, costly, burdensome, and often unhealthy.
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- Andersen AE: Practical Comprehensive Treatment of Anorexia Nervosa and Bulimia. Johns Hopkins, 1985.
Fairburn CG et al: Three psychological treatments for bulimia nervosa: a comparative trial. Arch Gen Psych 1991; 48-463.
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Russell GFM: Bulimia nervosa: an ominous variant of anorexia nervosa. Psychol Med 1979;9:429.
Waldholtz BD, Andersen AE: Gastrointestinal symptoms in anrexia nervosa: a prospective study. Gastroenterology 1990;98:1415.
Andersen AE, Cohn L, Holbrook T: Making Weight Men's Conflicts with Food, Weight, Shape & Appearance. Gϋrze Books, 2000.
Mehler PS & Andersen AE: Eating Disorders: Guide to Medical Care and Complications. Baltimore, MD, Johns Hopkins University Press, 2000.
Andersen AE, Watson T, Schlechte J: Osteoporosis and osteopenia in men with eating disorders. The Lancet, Saturday 3 June 2000, Vol. 355 No. 9219, pages 1967-1968, 2000.
Watson T, Bowers W, Andersen AE: Involuntary Treatment of Eating Disorders. Am J Psychiatry 157:11, 1806-1810, 2000.
Andersen AE & Holman JE: Males with eating disorders: challenges for treatment and research [Review]. Psychopharmacology Bulletin 33(3):391-7, 1997.
Beck D, Casper R & Andersen AE: Truly late onset of eating disorders: a study of 11 cases averaging 60 years of age at presentation. International Journal of Eating Disorders 20(4):389-95, 1996.
Margolis R, Spencer W, DePaulo RJ, Simpson SG & Andersen AE: Psychiatric comorbidity in eating disorder patients: a quantitative analysis by diagnostic subtype. Eating Disorders 2(3):231-6, 1994.
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** Note: many cases do not fit strictly into one of these categories, which are somewhat narrow, but may be equally serious and respond just as well to treatment. Example: weight loss of greater than 15% with continued menstrual periods; binge-eating less than twice a week. These cases are called "sub-syndromal", "atypical", or "eating disorder not otherwise specified" (EDNOS) by the current formal but overly rigid classification.
Last Reviewed 2005
Source: Arnold E. Andersen, M.D.
College of Medicine
University of Iowa Hospitals and Clinics
Disclaimer: This content is reviewed periodically and is subject to change as new health information becomes available. The information provided is intended to be informative and educational and is not a replacement for professional medical evaluation, advice, diagnosis or treatment by a healthcare professional.
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