How can a girl become smaller?

To answer your question about your legs when you lose fat you lose it all over eventually, if you store fat in your legs it will come off your legs only after it comes off everywhere else first. When you were a stick were your legs skinny? if yes then it's possible they will be skinny again when you lose weight...if you were skinny but your legs still looked more muscular then I'm afraid that's the shape of your legs. I heard pilates do help slim your legs down (but I have no experience with this, it could be complete bs, it's just what I heard).