I weigh enough (around 215) but I'm only 5' 10" so there's always the chance of being challenged.
I had a former colleague who outweighed me by a fair bit but I could take him down pretty quickly...he had the size and intimidation if we went somewhere, people would immediately be wary of him and dismiss me...it worked in my favor though.
In the beginning because of my size (probably weighed 160 when I joined) I was always picked as a demo for the instructor during our CQC (Close Quarter Combat) training but after a few times of me taking out the instructor they started to leave me alone. I was a black belt going into the military.
I'm 5'10" also...but 160-165lbs, and made it half way to black belt(we did white, yellow, orange, green, blue, purple, red, brown, black, I tested for blue.)
One friend made it to black...I tired of the relentless beatings, lol, but loved the simple self defenses I learned.
My friends and fought alot when we were younger, and fortunately not anymore(aging aches and pains, lol).
I always thought that being underestimated was my greatest advantage too.
I never underestimate anyone.
I have been suprised at the big scary guys who just fold up...and the small guys that would tear your ass to pieces.
My Dad always told me, "Just remember, no matter how big and bad you are, or Think you are...there's always going to be someone bigger and badder waiting around the corner".
Yep...and I Never started a fight in my life either.