I don't intend to sound mean, but I wish the people who are borderline morbidly obese (or over) wouldn't cosplay scantily clad characters. They're not doing themselves any favours, and I always feel embarrassed on their behalf thinking that they're going to be mocked for it. If you love cosplaying the character that much, I don't know, maybe try to diet and exercise for a few weeks before dressing up for any cons...

Same goes for anorexic-looking stick thin people. I really don't want to see your grossly prominent ribs and hipbones, it's truly just as bad as those morbidly obese people. Wear a bodysuit for padding or something. ;_;

Conclusion: There ARE ways to help you cosplay better, no matter your body/face type, if you're willing to put forth a bit of effort.