After gaining a few pounds over the holiday season, Jacinth is worried that she will not fit into her bathing suit when her swim team begins practicing and meeting for competitions in early spring. She decides to begin limiting what she eats and cuts back her daily food intake to one packet of oatmeal, two apples, and a can of diet soda for the entire day. She continues this eating pattern for almost a year before her friends and family intervene. Which of the following is the BEST descriptor of Jacinth's illness?

A: bulimia nervosa

B: diabetes

C: shingles

D: anorexia nervosa