I know this sounds weird, but some people just don't like food. Just like some people don't like exercise. It's sorta odd, but I mean, come on, we're human, we are odd! Just talk to her, see if it is a medical problem or if she just isn't hungry. There is no point of stuffing food in her face if she's just fine. She could have a slow metabolism and digest food slowly which causes her not to be hungry and all. I don't know, talk to her, that's about all I can say at the moment.