Zeena has an irrational fear of gaining weight. even though she is very thin, when she looks in the mirror, she sees herself as heavier than she actually is. she has recently lost a severe amount of weight to the point at which her friends, teachers, and parents are very concerned about her health. zeena fits the definition of one with

Anorexia nervosa

Explanation:

Anorexia nervosa is an eating disorder in which the patient develops an irrational fear of gaining weight. Their weight might be very well in the perfect range but they always perceive themselves as overweight. Hence they use extreme methods to lose weight. Anorexics will limit their food intake drastically, sometimes going as far as completely restricting eating up to many days. At this point, they can be very dangerous to their own health. Anorexia is differentiated from another similar eating disorder, Bulimia nervosa where the patient again has irrational fear of gaining weight but resorts to another methods to drastically lose weight. They often eat a lot in short amount of time and purge or use laxatives.