What condition is characterized by an intense fear of gaining weight, even when the individual is underweight?

The condition characterized by an intense fear of gaining weight, even when the individual is underweight, is anorexia nervosa. This eating disorder is marked by a distorted body image where individuals perceive themselves as overweight, regardless of their actual physical state. They may engage in extreme measures to lose weight, such as severe calorie restriction, excessive exercise, and other behaviors that undermine their health.

Anorexia nervosa often leads to significant physical and psychological consequences, including malnutrition, weakened bones, heart problems, and emotional complications like anxiety or depression. This disorder requires careful and compassionate treatment to address not only the physical aspects but also the psychological factors that contribute to the intense fear of weight gain.

In contrast to anorexia nervosa, other eating disorders such as bulimia nervosa involve cycles of binge eating followed by compensatory behaviors (like vomiting or excessive exercise) but typically do not include the same level of self-starvation or severe calorie restriction seen in anorexia. Similarly, binge eating disorder does not generally entail an intense fear of gaining weight; rather, it involves episodes of uncontrollable eating without subsequent purging. Therefore, the defining features of anorexia nervosa make it the correct answer in this context.