Which of the following characteristics is unique to anorexia nervosa when differentiating it from bulimia nervosa?

Cachexia is a characteristic that is unique to anorexia nervosa, primarily because it refers to a state of severe malnutrition and body wasting that results from prolonged energy deficiency. Individuals with anorexia nervosa typically experience significant weight loss and may have a body mass index (BMI) that is considerably lower than what is considered healthy. This state leads to muscle wasting and a decrease in body fat, which is a hallmark of the disorder.

In contrast, bulimia nervosa is characterized by episodes of binge eating followed by compensatory behaviors such as vomiting, fasting, or excessive exercise, which generally does not result in the same level of extreme weight loss or muscle wasting seen in anorexia nervosa. While those with bulimia may also struggle with body image and weight concerns, they often maintain a weight that is within the normal range or may even be overweight, so cachexia is not a typical characteristic of this disorder.

Therefore, the defining feature of cachexia aligns specifically with anorexia nervosa, as it highlights the severe physical consequences of the disorder that stem from inadequate nutritional intake and the body’s response to severe weight loss.