*Of course! If we're talking slim as in healthy looking. Slim people look fit, they look like they have self control and commitment to exercise. They look like they have their lives in order as they find time to (presumably) cook good food and keep fit while (presumably) doing all the stuff that healthy and attractive people do.
People who are unhealthily overweight look like they have no self control, and like they are either lazy or disorganised.
People like to be around vibrant and healthy people. It's natural.*
This kind of bullshit is why I tend to avoid threads like this. there is a definite pattern- poster complains about larger women (and it definitely seems to affect women more) being treated as if they are lesser, or disgusting. Some people agree and then the Body Police pile and explain that it's all fine, because fat people ARE disgusting and ought to be sneered at.