I've heard some pretty rude things come out of the mouths of people talking to others with very low self confidence. Whether you mean these things or not, remember that there are a few things you should be careful of avoiding when talking to an overly self-conscious person.
1.) Shut up, you're pretty.
Shut up? Well thanks person who I will never again trust with my deepest emotions. If I come to you upset about my body, it means I expect you to listen and talk to me, not tell me to shut up. Telling people they're pretty is great, keep doing that, but telling them to shut up definitely isn't. You may think you're being funny or maybe you just honestly think it's okay to talk to people that way, but it's not. After you tell me to shut up an then proceed to tell me my feelings are wrong, I will be hesitant to ever share a strong emotion or issue with you again for fear of being told to "shut up" because my feelings don't matter to you.
2.) I don't believe you.
This usually comes after I tell someone online my weight. It may seem flattering to you, but you telling me that you don't believe me about my weight just makes me feel worse about myself. I feel as if everyone else expects me to be small, and the fact that I'm bigger than you expect makes me feel like crap. If you want to flatter me then just tell me that the weight I tell you doen't bother you, i think that's much sweeter than telling me I'm lying about my own weight. (p.s., what girl would seriously lie to make herself seem FATTER?)
3.) You'd look better if you...
No. Just don't even start in on this unless the person specifically asks you for advice. I've been told that I'd look better if I dyed my hair back to brown which totally ruined how good the purple made me feel about myself. I've also been told I'd look better if I wore more makeup or tried to dress girly. The clothing that I wear now is comfortable for me and it makes me feel more ready to go out into the world. In dresses I feel sick to my stomach and worried about how I look. I'd prefer looking like a comfortable man than looking like a terrified and stressed out woman. Also, I have very little money. I come from a poor family so I can't afford fabulous clothing and good makeup, so even if I made an effort it still wouldn't improve me much.
4.) If you're so self conscious, why do you take so many pictures?
If you don't like the color brown why do you still eat brown foods? That's sort of like what you're asking. I take a lot of "selfies". I love looking into the camera and thinking about how beautiful I look on the tiny screen, even if I have to tilt it like the Leaning Tower of Pisa to look that way. You asking me that question makes me feel like I should stop taking pictures of myself, which is taking away one of the few outlets that actually makes me feel pretty.
5.) Wow, you're such an attention whore.
Uh, okay, and what does that make you for feeling the need to say that? Attention deficit? If I'm telling you that I dislike my looks, I don't expect to hear that I'm pretty. In fact, I don't want to hear tha I'm pretty, because then I'll just feel like I need to make myself look better to fit your standards. But you know what? If you're bitchy enough to call someone an attention whore for simply seeking out someone to talk to about their opinions then maybe I shouldn't care about what you think, because you don't seem like a person I should aspire to be like.
6.) Why don't you change it?
It isn't too easy to change your entire look over night. I have been working on my weight, my biggest insecurity, for awhile now. I've given up as much sugary food/drink as I can, I ask the adults of th ehouse to search for healthier options for me, and I've taken up more forms of exercise. I've only managed to lose 10 pounds so far, but that's better than nothing. It's hard to lose weight with my currect situation. We live off of food stamps, as trashy as that sounds, and I can't drive so I have no way to get a job to buy my own food. I have to eat whatever the adults buy, and my family isn't the healthiest. They don't care about their size, so I get stuck gaining more weight because of their food choices. I also have hypothyroidism, which makes exercise alone hardly enough to keep my weight steady. I have been trying for ages to change mysself, but it just doesn't seem to be working. So before your advice is "just change it", you should look at the reasons that changing it might not be too much of an option.
7.) Everyone has insecurities, stop acting like a victim.
You're right, everyone does have insecurities, so why am I not allowed to express mine? Using "everyone has insecurities" as a reason to stop worrying about them is like telling a crying person "everyone breaks their leg at some point little Timmy, stop being such a wimp."
8.) People these days are so sensitive, back in my day people had a tough outter skin!
Well back in your day you were probably a douche, so at least something has stayed the same since then. I don't care about what people in your day had, because this is a new point in time. People have changed, and it just so happens that the world has gotten more sensitive. Yes there are people who overdramatize things way more than necessary, but me not wearing bathing suuits because of my weight isn't some stupid overdramatization based on some silly remark. You make have a tough outter skin, but mine is like paper. (Also, it can cut you. Meaning I will gladly cut you.)
If you have an overly sensitive friend, try to remember these things if you want to avoid any unecessarily hurt feelings.