Ana is a short term for Anorexia. Anorexia or Ana is an eating disorder when someone cuts food rations very low, skips meals, starves/fast to become skinny. Ana could be knows as an eating disorder or a life style choice.
Ex 1:
G: (Name) in my 3rd class never eats.
B: I heard He/She passes out alot becauae of it.
G: Thats crazy, she doesn't look to skinny.
B: Maybe she is starting to be Ana.
Ex 2:
G:In the locker rooms during PE (name) was changing and all her bones were sticking out.. She looked.... Dead.
B:Thats horrible, (name) should eat more.
G:I think she has Anorexia..