Okay so this is weird....?

This girl in my 6-7 block [a 2 hour cl counting as 2 periods] eats all the time. She's really skinny. And when she eats, she like...it seems like she has a rush to eat or something. Like one time when we were working on a project she went over to the trashcan and had a few bites of applesauce and threw it away. Then one time she had half an apple. Then today she was like rushing to get out her food when we got back from field trip, and ate a handful of trailmix all at once. What's wrong with her?... This doesn't seem normal