You have a lot of options. You can not mention it, you can refer to it as making healthier choices instead of trying to lose weight, or you can explain to them why it's important to you. I think it's tough for people to remember that everyone is different, and that just because you think I look fine, I might still not be comfortable. I'd also say too to remember that for the most part these people say these things because they love you and want to make sure you know it.