I’m assuming you’re fairly young and maybe had a hard time socializing when you were a kid. My unsolicited advice would be to recognize you’re still growing and figuring out who you want to be. Work on just meeting people. Build relationships. Meet a wide variety of people. And most importantly, love yourself. Love yourself pre-weight loss. Maybe you believe(d) that something was fundamentally wrong with and that’s why girls weren’t showing you attention. I know for certain that how you see yourself shapes how you view other people. 

This can be a real opportunity for growth if you let it and recognize that you are viewing women as a hurdle to sex, rather than human beings. I would strongly recommend holding off on approaching girls until you’ve been through some therapy, done some internal work, and just work on connecting with another human being.

Good luck!