Teens: (Girls)How can I revamp myself for Freshman year?

Okay so this year I am planning to lose weight and hopefully grow a few inches. In addition, I would also like to appear differently next year. Right now I am what you would call a "loser" or an "outcast" or whatever. I mean people like me and stuff and they think I am funny, nobody really hates me, they just know I am not a good talker and they probably feel awkward talking to me because I never really have anything to say and I never know what the hell to talk about. I spend the lunch period sitting w/ people who look like they feel sorry for me because I never say a word and I am tired of trying to be happy and pretending I am. Everyone is really nice in my school, I just have trouble pushing myself, and I do not want to, but I need to, do you think I could go from loser to normal in one summer? What can I practice to help me make friends and push myself? Thanks!!!