It's their own insecurity. It's a little different for me because I'm Asian and when you run in Asian circles the majority of them are anywhere from average sized to slender. Almost every girl (Asian or otherwise, now that I think about it) I know is a skinny bitch so now you're comparing skinny bitches to slightly skinnier bitches.

One of my closer friends is a hater if people are "better" than her but/and has "misery loves company" issues. Three of us started a "let's all get fit for the summer" campaign in January and she went on and on about how she wanted to look Victoria Beckham skinny (at her skinniest) and only those who are that skinny can wear certain clothes etc. because she actually used to be that skinny a few years ago. Well due to stress and lack of focus she was unable to lose weight and ended up gaining a few. I ended up achieving my goal weight a few months back and when I was out with family I sent my friends a photo of myself and my nephew going, "Hey guys don't I look skinny here". Her reply was "omg you look TOO SKINNY. You need to stop losing weight now." Like, I guess if she can't look like a runway model no one else gets to be skinny?

You just have to accept that it's really them and not you and go on with yo bad self.