Like bro said it may be a chance that she's tryna bulk. Is she a gym girl gym girl? Because if that's the case more than likely she's trying to gain more muscle as opposed to fat.
On the other hand if she's eating a lot with you and initiating belly rubbing, then there's also a chance that she may secretly be a feedee, or wants to be? I'll just try to look into it more and bring up the feederism topic once you feel comfortable enough.