Which of the following symptoms may be indicative of anorexia nervosa?

The presence of amenorrhea is a significant symptom that may indicate anorexia nervosa, particularly in females. Anorexia nervosa is characterized by restrictive eating patterns, an intense fear of gaining weight, and a distorted body image, leading to severe weight loss. The physiological consequences of extreme weight loss and malnutrition can result in amenorrhea, which is the absence of menstruation. This symptom reflects the body's response to insufficient energy intake and nutritional deficiencies, as the hormonal balance necessary for menstruation is disrupted.

In contrast, excessive appetite does not align with the behavior typically seen in individuals with anorexia nervosa, who are characterized by a significant reduction in food intake. Mood swings and insomnia can be related to a variety of mental health conditions and are not specific indicators of anorexia nervosa. While these symptoms may arise as a result of the stress and physiological changes accompanying the disorder, they are not defining features. Thus, amenorrhea stands out as a key symptom that can help in the diagnosis of anorexia nervosa, particularly in women.