The upper limits on Fat-Free Mass (aka Lean Body Mass)

My curiosity on what are the upper limits of muscular development in humans , and paying close attention during my Exercise Physiology Class during the lecture on body composition. The research has pointed me into the direction that contrary to popular belief among bodybuilding websites that one can just balloon up in size past 300+lbs of muscle the sad fact is that most of the extra weight is just plain old fat. That there is in fact an upper limit on the amount of fat free mass and individual can obtain which is a function of human physiology.

One of the sources which abstract I looked at is http://onlinelibrary.wiley.com/doi/10.1002/ajhb.1310060509/abstract from the American journal of biology which looks at the FFM (Fat-Free Mass) upper limits in sumo wrestlers , bodybuilders, and untrained individuals.

Obviously the sumo wrestlers had the highest FFM due to the fact in order to carry around all that extra body fat the body will have to make adjustments in connective tissue etc... to just help them get up out of bed every day and walk over to the bathroom.  The sumo wrestlers therefor represent the highest possible FFM attainable they averaged to about .61 kg/ cm.  The estimated high end FFM (kg)/ Height (cm) ration attainable is .7 kg/ cm.

Using myself as an example assuming that I was able to reach the upper limit I'm 5'9 which is about 175 cm , using the .7 kg per every cm I would theoretically be able to reach 122.5 kg or about 269.5 lbs of FFM mind you I would probably also be at 30-40% BF like the sumos in the study. In my lecture class my professor mentions 275 lbs as the upper limit in FFM again for one to naturally achieve this they would have to be carrying a substantial amount of BF% to warrant the extra connective tissue etc..  I don't know about you but being obese to achieve the upper limits of FFM is not something I want to shoot for.

I have also come across something called the FFMI which is analogous to the BMI the difference is that it takes FFM (kg) / Height (meters)^2.   Apparently it has a strong correlation to steroid use. Which I found pretty interesting noting that many so called naturals / supplement companies would have you believe you can reach the upper limits of FFM while maintaining low BF%

"The normalized FFMI values of athletes who had not used steroids extended up to a well-defined limit of 25.0. Similarly, a sample of 20 Mr. America winners from the presteroid era (1939-1959), for whom we estimated the normalized FFMI, had a mean FFMI of 25.4. By contrast, the FFMI of many of the steroid users in our sample easily exceeded 25.0, and that of some even exceeded 30. Thus, although these findings must be regarded as preliminary, it appears that FFMI may represent a useful initial measure to screen for possible steroid abuse, especially in athletic, medical, or forensic situations in which individuals may attempt to deny such behavior."- http://www.bodyrecomposition.com/research-review/fat-free-mass-index-in-users-and-nonusers-of-anabolic-androgen-steroids-research-review.html

I also found a calculator which helps you determine your genetic potential of muscular BW at certain %BF
http://www.weightrainer.net/bodypred.html   it use anthropometric measurments of your wrist and ankle diameters along with your height and desired %BF to calculate your BW at it's upper muscular development obtainable for naturals (i.e. non - steroid users)