I have a question which I've seen many times but never really asked. How is it some people are so muscular but are very light. I have two friends who are both about 6'1-6'2, and both weigh about 170ish, but on is WAY more muscular than the other, and the one who's not as muscular isn't fat at all. I see this alot especially in lower weight classes of MMA, whats up? Isnt muscle supposed to weigh more than fat. And some people look really skinny, but weigh alot more than they look? Are their bones denser or something? Whats up?