cory, i trained natty for the past 15+ years...started out in powerlifting, went to martial arts but never stopped lifting weights...I always felt like i needed the extra "armor" of added muscle to my frame. My natural weight is about 145 (I'm 5'7"), but Ive consistently maintained a bw of 165-170 with bf of 10% +/- a few %'s with consistent weight training.
I am by no means an expert, and i'm sure some of the guys on here can give you a much more scientific answer, but my experience is that I seem to reach a point where my recovery kind of ,well for want of a better word, plateau's. I can work out more, or more effeciently, or in different ways, I have tweak my diet, rest patterns, weight/set/rep/frequency.... but I reach a point of equilibrium past which I simply cannot gain quality weight. I can't tell you how many times over the years I've overtrained or burned out trying to push my personal limits....I think for me personally (and for most of the people I've trained with over the years) it all comes back to hormonal levels and genetics, specifically in the number and type of muscle fibers you carry. Not saying these factors are the end-all be-all, but with natural training I think these are the limiting factors as long as diet, training, mental toughness etc are all in order and you experiment and adapt over time.
Apparently our bodies have self regulating mechanisms (primarily hormones) that cause us to reach points of diminishing returns...where is the survival value in carrying an extra 50+ lbs of useless (for purposes of survival) and expensive (in re to energy intake requirements) muscle tissue? I think this is the crux of the problem we face in trying to change the amount of muscle tissue our bodies will create naturally.
