Here's a big secret that most people figure out sooner or later: the people who value looks most are the only ones you don't want to get involved with.
I'm not saying looks aren't important. They are. What I'm saying is there's no such thing as a perfect body, and there's no reason to make drastic changes to your own.
There's no girl every guy likes, and no guy every girl likes (no guy every guy likes, no girl every girl likes). Everybody has other people who like them, and nobody has everybody like them.
And I'm not talking "despite your looks, I like you for your personality." No, I mean, "Wow, you have a hot body!"
We're too eager to set standards for what looks good and what doesn't. But the fact is, we all prefer different things. Don't be taken in when people tell you have to dress a certain way, or act a certain way, or that "well I'm sorry, you'll never have somebody because you're just too plain ugly!" Chances are, the person who told you that was too cold-hearted to ever get in a decent relationship.
You can spend your life trying to fake being someone else, working hard to be who you're not, fighting every day the desire within your heart to be you. Or you can tell society to shove it and celebrate who you are, be beautiful (or handsome), and enjoy your life because dang it, it's your life, and you only get one shot.
If you don't like the way you look, and you want to change, fine, but do it for you, don't do it for somebody else. If you decide you need to slim down to be healthy, that's perfectly acceptable. But don't starve yourself because some dick thinks you're fat.
Regardless of your looks, there will be people who will be attracted to you. There probably already are; there's a lot of shy people out there who will never say anything. Of course, hopefully attraction won't be the sole basis of your relationships.