Anorexia Nervosa is an eating disorder where the person has an extreme fear of gaining weight or constant worry about their calorie intake.
In the DMS 4 one of the criteria to be diagnosed with anorexia was being underweight, but this was changed in the DMS 5.
There are different kinds of anorexia nervosa: the restricting type and the binge/purging type.
NOTE: Purging includes but is not limited to vomiting, taking laxatives, and excessive exercise.
I hope this helped!
I know quite a lot about anorexia nervosa, so if you would like additional information let me know in the comments
~Just a girl in love with Shawn Mendes