Why am i not hungry anymore i use to eat all the time now i cant even look at food?

Ok so i use to eat all the time! I would wake up eat breakfast get to school eat lunch (meatball sand which, ice cream and a rice krispy treat). Then i would get home and eat what ever was around the house until dinner then i would eat like 3 plates of dinner. Then a snack after that. But over the past week just looking at food makes me full and i cant eat. My mom wants to send me to therapy for anorexia but i'm not anorexic. I went from 116 pounds to 105 pounds and that's not that bad other then i am 5'8" =/ Anyone have any ideas?