Does masturbating cause a person to lose weight?

I've been masturbating for few years now, and I don't know if this keeps me from gaining weight. Some people told me I look the way I do because I masturbate so much. I've heard semen contains protein. Is there any relation?

There is no relation. Semen does contain protein, but if you ate one peanut per ejaculation you'd more than make up for it. Good luck gaining weight (and masturbating!).