I told her that being skinny =/= perfection, but she acts like I basically get what I want and live a good life bc I'm skinny... 

"No wonder guys like you all the time, it's bc you're skinny"

"You only run fast bc you're skinny"

"You can work out longer than me bc you're skinny"

"You must be so happy being skinny"

"Why aren't you happy with your body? You're skinny."

It's basically stuff like that, and I hear it A LOT...I feel like all these comments she's making towards me is bc she's insecure? I don't mean it in a bad way, but I don't know why else she would say all this stuff. Maybe I'm just jumping to conclusions? Sometimes she would make jokes about me being skinny, and I used to be so insecure about my body and weight that I would cut myself, but I've learned to be more accepting and love my body. The first couple of times she would make fun of me, I wouldn't say anything. We've been working out for a while, and I thought I made some great progress by closing my huge thigh gap so I was talking to her about it, and she made fun of me being skinny again and said sarcastically "uh huh, I really see that progress...."

She refuses to believe that I have stretch marks bc apparently "skinny people can't have stretch marks" and even after telling her how stretch marks form, she still doesn't believe me for some reason? 

She was having a hard time losing weight bc she admitted that she couldn't stop eating junk food, so I told her about the time I had an eating problem and just wouldn't stop and it made me seriously unhealthy and how I solved that problem, but she didn't believe me and said "you're skinny, but you should be eating more anyways"

I just don't know what to do about this. I've asked her to stop multiple times, I've tried ways to make her feel more positive and secure towards herself and her body, and she's a really good friend but this stuff needs to stop already and I don't know what to do. I feel like I'm overreacting, but she talks about me being skinny way too much, even in situations that have nothing to do with weight or bodies.