Diagnosis of Anorexia Nervosa

Energy Restriction and Body Weight

The fundamental criterion for the diagnosis of anorexia nervosa is persistent restriction of energy intake.

This leads to a significantly low body weight relative to what is considered minimally normal for the patient's age, sex, developmental course, and physical health.

Clinically, this is not simply being "thin," but a condition where the body mass index (BMI) drops to levels that compromise physiological health (e.g., a BMI of less than 17 in adults is considered mild, while less than 15 is extreme).

The person maintains this restriction despite the obvious negative consequences to his or her body.

Intense Fear and Perceptual Distortion

The second component is an intense and irrational fear of gaining weight or "getting fat", even when the person is in a state of evident malnutrition.

This fear does not diminish with weight loss; paradoxically, it usually increases.

Added to this is a profound alteration in the perception of one's own body image (dysmorphia).

The individual eva luates his self-worth based almost exclusively on his silhouette and weight, denying the medical seriousness of his current low weight.

Self-eva luation is distorted such that extreme thinness is perceived as an achievement of self-control and any weight gain as an unacceptable moral failure.

Classification of Clinical Subtypes

The DSM-5 distinguishes two main presentations. The restrictive type is characterized by weight loss being achieved primarily through extreme dieting, prolonged fasting, and excessive exercise, with no recurrent episodes of binge eating or purging within the past three months.

On the other hand, the binge/purge type implies that the individual, in addition to restricting, resorts to binge eating episodes followed by immediate compensatory behaviors, such as self-induced vomiting or the use of laxatives and diuretics.

It is crucial to differentiate the latter from bulimia