Yes I can understand your concerns. The thing is when we care about someone and when we share ourselves with them, we consider it a special moment and we do not want to feel criticized. I think first your have to realize that this person was wrong for what they said. If they love and care about you then the last thing they should want to do is say something about your looks after you have been together. It is disrespectful to say the least.
Also understand that not one's body is perfect. We all have imperfections. Therefore, try not to let it affect you too much. No one's looks are perfect, no one's body is perfect. Not matter how skinny, they are or how much they work out, there is always something that could be better. With that being said. Intimacy is not about looking for the imperfections. It is about being together with someone you care about and enjoying that moment. You should try expressing this to the person that you were intimate about. Let them know they it hurt your feelings, it is possible that they meant not harm by it and they may care about you just the way you are. If they don't then perhaps you should evaluate weather this person is for you. Because as we grow older looks changed, and they should love the inside of you, and not just the out.