My 9 year old does stuff like this too. Well, as much as she can, the scales are in my bedroom under the bed gathering dust cause I hardly ever use them and she doesn't know they're there, but she will do things like say she's getting fat, or trying to avoid eating much for dinner etc. She is also starting to show signs of the onset of puberty.

Best way I've found of handling it is to not make a big deal out of it, keep talking to her about healthy food choices and making sure she's taking part in a range of activities (dancing, sports etc). As well as constantly reassuring her that she's fine just the way she is, and that it's natural as she gets older and starts growing into a woman that she will get a little curvier and so on.