Anorexia nervosa and bulimia nervosa are the two major eating disorders. They are complex syndromes with considerable psychiatric and medical comorbidities. Current diagnostic criteria for anorexia nervosa and bulimia nervosa from DSM-IV (1) are shown in Tables 5.7.2.1 and 5.7.2.2. For those patients who have serious problems with eating behavior but do not fall into the diagnostic categories of anorexia nervosa or bulimia nervosa, the DSM-IV has designated a category of “Eating Disorder Not Otherwise Specified” (EDNOS). Most cases of eating disorders have an onset during adolescence.

There are four major criteria which define anorexia nervosa. The first criterion is a guideline for defining weight loss, since there is no specific amount of weight loss associated with the other symptoms that constitute anorexia nervosa. Therefore, an adult is considered “underweight” if the individual weighs less than 85% of a weight that is considered normal for that person’s age and height. For children up to the age of 18, pediatric growth charts should be used. Some children may not have weight loss but still weigh less than expected weight because they have failed to make weight gains during a growth in height.

There is no consensus on how weight loss should be calculated, especially with adolescent patients. Some clinicians calculate weight loss below a normal weight for age and height and others figure the amount loss from an original baseline. Body mass index (BMI) is height in meters squared divided by weight in kilograms. This measure is a standard score that somewhat corrects for height and different body build. This index has the advantage of not being subjected to cultural influences. Generally, a BMI of less than 17.5 is regarded as being underweight. A BMI between 25 and 30 is considered overweight and over 30 is labeled obesity.

The second criterion, “intense fear of gaining weight,” is present even during emaciated states. Anorectic patients often deny this fear since they are resistant to treatment and thus, their fear of gaining weight must often be inferred by reports of their behavior which reveal rigorous attempts to prevent weight gain such as severe food restriction and exercising.

The third criterion, pertaining to body image disturbance, has evolved into a more complex concept. The significance of body weight and shape are greatly distorted in these individuals. Some feel globally overweight and others realize they are thin but feel certain parts of their body, especially the abdomen and thighs, are too fat. The distorted significance of body weight and shape is related to a feeling of being very ineffective. Losing weight and being thin is one area in which these individuals can be effective and in control. The latter undoubtedly influences their denial of the serious medical complications of their malnourished state.

The fourth criterion for diagnosis of anorexia nervosa in the DSM-IV is amenorrhea. In some adolescents who have never menstruated, the amenorrhea is primary and menarche is delayed by the anorexia nervosa. Amenorrhea can appear before noticeable weight loss has occurred (2). Because it is difficult to obtain an accurate history of menses and because of the great variation associated with weight loss in menses, some academicians are advocating abolishing this criterion.

There are two subtypes of anorexia nervosa: the restricting type and the binging-purging type. Studies have consistently demonstrated that impulsive behaviors including stealing, drug abuse, suicide attempts, self-mutilation and promiscuity are more prevalent in anorectic— bulimics compared with
anorectic restrictors. Those with anorexia binge-purge type also have a higher prevalence of premorbid obesity, familial obesity, debilitating personality traits, and specific medical complications compared with those anorexia restrictive type (3,4,5).

The criteria for bulimia nervosa are more arbitrary and less specific than the criteria for anorexia nervosa. There is no consensus on what constitutes a binge and how frequently bingeing must occur to warrant a diagnosis of this disorder. In the first criterion for bulimia nervosa in DSM-IV, binge eating is defined as eating more food than most people eat in similar circumstances and in a similar period of time. The sense of losing control is a significant subjective aspect that needs to be present. The second criterion, which is the recurrent use of inappropriate compensatory behaviors to avoid weight gain, usually means self-induced vomiting. However, bulimic patients often use cathartics for weight control and have an eating pattern of alternate binges and long fasting periods. The third criterion designed to address chronicity and frequency is not based on specific research but rather clinicians’ consensus for obvious impairment of functioning. The fourth criterion acknowledges that bulimia nervosa patients are also concerned about their body shape and weight and tend to place excessive estimation of their worth in terms of appearance. The fifth criterion of bulimia nervosa differentiates the latter from the binge-purge subtype of anorexia nervosa. The diagnosis of bulimia nervosa is also subtyped into a purging type for those who regularly engage in self-induced vomiting or use of laxatives or diuretics and a nonpurging type for those who use strict dieting, fasting, or rigorous exercise but do not engage in purging behaviors. Bulimia nervosa patients who do not purge tend to have less body image disturbance and less anxiety concerning eating compared with those who do (6).