If I were in your position, I think that i'd get another group of friends and start hanging around with them too. You don't have to ignore her 100% but when she says irritating things, make eye contact with her and hold it and then dont laugh or smile or shrug it off. Then say "is that supposed to be funny?" or walk away- make it clear that you're not taking her stuck up attitude and annoying behaviour. Slowly, if not quickly, she'll start to feel in less control and stupid. Just because she thinks it is acceptable that doesn't mean it is. And by the way, if one of my mates said "give me some of your flab" I'd prob get vexed after her saying it loads and say "really, do you want it that bad? I think you look better the way you are- like one of the starving kids in a 3rd world country"ggrrrrr.