mischeif maker- be VERY careful before assuming someone is anorexic. An anorexic person has problems with body image and will not eat junk even if they are hungry. Most anorexic girls will refuse to eat at all in front of other people. That girl is not anorexic, it could be she has some digestive problem or forgets to eat but anorexia has to do with body image, not just not eating.
If she eats junk when she’s hungry, she is definitely NOT anorexic. She is just on the opposite extreme of those who always feel hungry, she probably doesn’t naturally feel hungry. (I’m like this too, sometimes I don’t realize I need to eat until I start to feel weak.)