What eating disorder is characterized by restriction of intake and fear of gaining weight, with a BMI less than 17?

The eating disorder characterized by restriction of intake, an intense fear of gaining weight, and a body mass index (BMI) of less than 17 is anorexia nervosa. This condition involves a profound preoccupation with body weight and shape, leading individuals to severely limit their food intake. The fear of weight gain is often disproportionate to their actual body weight, which can result in significant physiological and psychological complications.

Individuals with anorexia may engage in various behaviors to maintain their low weight, including excessive exercise or the use of diuretics and laxatives. The diagnosis typically requires meeting specific criteria, including a markedly low weight, an intense fear of gaining weight, and a distorted body image. The severe restriction of intake is what distinguishes anorexia from other disorders such as bulimia, which involves episodes of binge eating followed by compensatory behaviors, and binge eating disorder, which is characterized by recurrent episodes of eating large amounts of food without the regular use of compensatory behaviors. Orthorexia, on the other hand, is not an officially recognized eating disorder but refers to an unhealthy obsession with healthy eating, which is different from the weight-related concerns seen in anorexia.