if you are fat and having sex with your shirt or clothes on, ask yourself why. Do you think the other person won't notice you are fat because of a tiny layer of cloth? Do you think they haven't already assessed that you are?
Unless they are completely oblivious, people can guess the shape of your body even if you cover it, if they are choosing to f-ck you it's because they either are ok with it or actively liking it. You are only depriving yourself of the pleasure physical contact give. You won't feel better about yourself if you don't at least start by doing something that allows you to do so. Undressing when having sex is the basis - it's a safe space, or it should be, and the exposure you will undergo will be totally worthy. Let their hands slide over your body and caress you, feel the other person over your chest. Enjoy every single shiver, make them know how your breath and heartbeat changes because of them. There is a territory yet uncharted for the both of you.
