Defining severity in anorexia nervosa (AN) is a significant challenge, therefore in 2013, the DSM-5 [1]—in line with the new specifiers for mental disorders—introduced body mass index (BMI) specifiers, including mild (i.e., BMI ≥ 17), moderate (i.e., BMI between 16 and 16.9), severe (i.e., BMI between 15 and 15.9), and ...