Most people I know have been in situations similar to yours...that is, having to withstand comments that make them feel uncomfortable. I think you have to first figure out why they are making such comments—often times, it is just to get a rise out of you and to make you angry. Sometimes, it’s just because they are being dumb—and they know it. I think it's important to contextualize their motivation before making a comment. I think humor is sometimes the best response (but that's not always easy to come by). For instance, depending on their shoe size saying "then why are YOUR feet so small?" Next, I think no response is the best response—since it's likely that they are trying to get a rise out of you, when you don't give them that they get frustrated. I know these comments can be hurtful, but knowing what the intention is takes some of the sting out of it.