Differences between Anorexia Nervosa and Bulimia Nervosa

Anorexia nervosa vs. Bulimia nervosa

Anorexia nervosa and bulimia nervosa are distinct psychiatric conditions classified as eating disorders in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) and the International Classification of Diseases (ICD-11). Both conditions involve an intense preoccupation with body weight and shape, but they differ in their behavioral patterns and physiological presentations. Anorexia nervosa is primarily characterized by self-starvation and significant weight loss, while bulimia nervosa involves a cycle of binge eating followed by compensatory behaviors such as self-induced vomiting or the use of laxatives.

Comparison Table

Category	Anorexia Nervosa	Bulimia Nervosa
Body weight	Significantly low BMI (under 18.5 for adults)	Typically normal weight or overweight
Binge eating	Occurs only in the binge-eating/purging subtype	Required for diagnosis (at least once weekly)
Primary behavior	Food restriction and avoidance	Recurrent episodes of overeating
Purging	May be present in some cases	Present in nearly all cases
Physical signs	Lanugo, bradycardia, and amenorrhea	Dental erosion, swollen salivary glands, and calluses on knuckles
Awareness of illness	Often denied by the patient (egosyntonic)	Often recognized as abnormal (egodystonic)
Age of onset	Early to mid-adolescence	Late adolescence to early adulthood

Venn diagram comparing Differences between Anorexia Nervosa and Bulimia Nervosa

Behavioral differences

Individuals with anorexia nervosa exert extreme control over food intake. The restricting subtype involves weight loss achieved through dieting, fasting, or excessive exercise. The binge-eating/purging subtype involves periods of food consumption followed by purging, but is distinguished from bulimia by the presence of a dangerously low body weight.

Bulimia nervosa requires the presence of binge eating, defined as eating an amount of food that is definitely larger than what most people would eat in a similar period under similar circumstances. These episodes must be accompanied by a sense of lack of control. To prevent weight gain, the individual then employs compensatory methods. Unlike anorexia, the weight of a person with bulimia typically remains within or above the expected range for their age and height.

Physiological impacts

The medical complications of anorexia nervosa stem from chronic malnutrition. These include the growth of fine hair on the body (lanugo), low heart rate (bradycardia), and the loss of menstrual cycles in females (amenorrhea). Severe cases can lead to bone density loss and heart failure.

Bulimia nervosa complications are often related to the method of purging. Frequent vomiting exposes tooth enamel to gastric acid, leading to permanent dental decay. Repeated use of the fingers to induce vomiting can cause calluses on the back of the hand, known as Russell's sign. Electrolyte imbalances, particularly low potassium levels, pose a risk for cardiac arrhythmias in bulimic patients.