Should I approach a crush?

I am crushing hard. I just found out this guy is gay but he is out of my league. I'm overweight and just not an attractive guy. It hasn't really been a problem since all I have ever been after was sex and thats not difficult to get. I know him through friends and I've been in a professional work setting with him and now we have a class together. I never would have assumed he was gay, and people think the same about me. I haven't felt like this in a while and I feel really anxious. I'm certain that he would reject my advances but I feel like if I don't act, I will regret it. It would just be so odd to have to be around him after that rejection. Any advice?