How can I turn off the nasty comments my mind makes each time I see a fat person?

I can't help it. Whenever I see one my mind makes all these nasty comments! I don't voice them aloud. But I feel so disgusted, with my mind for being so mean and them for being so fat. But I can't control these thoughts! I don't want my mind to make rude remarks everytime I see someone fat, whether I'm talking to them or pass a glimpse of them as they're driving by. I'm dead serious about this question even though it sounds kind of mean/troll ish. But I don't conciously think them they just pop into my mind so I don't know how to make them stop. And if they are wearing shorts they don't even have to be fat, just not thin, I hate that my mind makes all these comments but I can't stop it. And I don't think anything about guys unless they are HUGE, but even if they are chunky I don't think twice, it's just girls. How can I turn off these mean comments?