I am not sure what your dating profile pictures look like, but do they hide your excess weight? If that's the case, meeting you in person may be a bit of a shock. It is very easy these days for bigger people to take pictures of themselves at good angles that hide their weight.

Also, it's not necessarily shallow to not be physically attracted to bigger people. It's all about preferences. If your pictures are camouflaging the weight, I'd suggest putting something up that shows your whole profile, not just your face, so that these guys are aware of what you genuinely look like. There will be no surprises, and you'll know that the guys you go on dates with are totally fine with your size.