Griz, I hear what you're saying.
I had friends who treated women like crap. They were mean to girls they dated and it seemed as though the girls couldn't get enough of this sort of treatment.
That says a lot about those girls. Think of how many end up with jerks who beat them or run around on them. That's what they end up with when they choose those guys. Then if they finally break up with a person like that, it isn't long before they choose another of the same caliber.
That is an example of low self-esteem.
The comments Ouch and the others made previously are also true. If you are unsure of yourself in a social situation, it's really obvious. The best thing you can do in my opinion is to develop all the other facets of yourself to the fullest extent. Become well read, watch the news, have a knowledgable opinion on important topics, have interesting hobbies, develop a close spiritual relationship with God. I happen to be a believer, so that's just my opinion.
Let the least important thing about you be the physical. Don't let HOW BIG YOU ARE define you as a person. Just in case these guys are correct and you have some insecurities that are showing and you don't feel you have 'game' with women, abandon that thinking. Don't play the game.
If you are a nice guy, go where the nice girls are. Meet them at places that interest you. For me that was in college classes, in the cafeteria, at sporting events, in the gym, laying out in the sun, or in study groups or at church. I enjoy reading and it turns out there are a lot of women who visit book stores like Barnes and Noble etc.
I did meet some women when I bounced at bars but it didn't appeal to me to see drunk girls acting like loud whores. I've never had a girlfriend I met at the bar.
Lastly, if you choose to ignore all this advice or think it doesn't apply to you, then lift up your shirt right now. Do you have abs? If not, lose some lard.
Make sure your "BIG" isn't "FAT". Many make that mistake.