Limits of Muscle Mass

This is a topic that’s argued endlessly: how big can you really get as a natural? What’s the limit for a truly natural bodybuilder?

The mainstream viewpoint, promoted by the media and held by naive gym-rats, is that even the biggest guys can be totally clean. Guys that are “average” height, say 5’7 to 6′ or so, holding less than 8-10% body fat while being 250 lbs or heavier. It’s nice wishful thinking, especially for the anti-doping zealots and the denial crowd, but no. Just no.

There’s a study that I like to use to illustrate the point:

Fat-free mass index in users and nonusers of anabolic-androgenic steroids.

To simplify, they took a large sampling of naturals and of steroid users then normalized their fat-free mass index (FFMI) scores. They found that the naturals all topped out at an adjusted score of 25, while the steroid users could easily cap 30. They also took bodybuilders from 1939-1959 and found that they had an average score of about 25.4.

Going by these findings, a guy that’s 5’7 (170cm) is going to have a limit of 72kg (around 160 lbs) and a 6′ (183cm) tall guy will be limited to around 84kg (184 lbs) of muscle mass. In between those, the limit is going to scale accordingly. A lot of people don’t like this study, for obvious reasons. Not only does it become pretty easy to figure out who might be using drugs, it also shatters the dreams of a lot of insecure guys aged 18-25 that see the big boys in the muscle rags and think that they, too, can look like that if only they work hard and take whatever magic pill they see in the ad-copy.

Obviously there’s a little more to this than just “working hard”. We have to throw in “wink wink, nudge nudge”.

Another good corroborating source comes from Dr. Casey Butt’s excellent WeighTrainer website. While it’s not research, his maximum bodyweight calculator and maximum drug-free measurements are both based on very sound methodology. It doesn’t hurt that the conclusions line up with the FFMI results, either.

Now, I’m a pretty small-framed guy. I’m around 5’9 (175cm), with a wrist measure of 6.5″ and ankle of 8.5″ around (I just measured while writing this to be sure). I can connect thumb to forefinger on both wrists. I was all of 125 lbs when I started lifting weights right after high school, though I’ve been as heavy as the low 220s, and right now my body seems very comfortable right at 200 lbs – it’s a lot of effort to get weight to move either way. I will add that I’m not super-lean, either. Hardly fat, especially by modern society, but 18-22% is probably about right.

I’ll take the high-end and assume that right now, in my addled, injured, and lazy state, I’m holding maybe 75kg/165 lbs of LBM. For my heaviest at 220 lbs, I’ll assume around the same and figure I was holding maybe 82kg/180lbs or so. Running that through the FFMI check (and note that I’m not using their correction factor, just for ease), I get a score of 24.5, while at 220 lbs, the score was 26.8. Make of those numbers what you will.

What about Casey’s calculators? For the maximum bodyweight calculator, my measurements and a bodyfat level of 10% give a score of 188.9 lbs. Maximum measurements at that weight/body fat:

Chest: 45.5 in
Biceps: 16.3 in
Forearms: 13.1 in
Neck: 16 in
Thighs: 24.2 in
Calves: 16.3 in

Now, I’ve got most of these beat already, some by a good margin. However, these are lean values, with the fat stripped off, so there’s going to be a pretty substantial difference. The 188.9 lbs sticks out to me – that’s maximum body weight at 10%, not maximum muscle mass. The max LBM would be ~170 lbs at that weight and BF% – and lo and behold, what do I see?

Going by Casey’s analysis, the maximum measurements for someone of my frame at a “reasonable” bodyfat level (8-10%) are thus:

Chest: 46.8 in
Biceps: 16.9 in
Forearms: 13.4 in
Neck: 16.7 in
Thighs: 25.8 in
Calves: 17 in

Obviously, I’m not far off the limits for any of these measures – FFMI is right at the border (and has been briefly above it by a fair degree), maximum measurements and total body weight are all right up there.

I’m not telling you this to make myself look better; not even remotely. I’m more or less at my limits, and I still haven’t made the top 50%; and that’s OK. Not everybody’s meant to be at the top.

My point here is that we have to keep perspective. Even now, realizing this, it’s easy for me to get into a mentality where I feel like I’m too small and want to be bigger – but the numbers just don’t lie. Physiology is made up of some hard rules. Without drugs in the mix, further growth is just not likely to happen – and this probably explains why any attempts to “bulk” just result in me getting fatter. My body just doesn’t want to gain any more mass. It’s about as impressive as I can make it, in terms of muscle mass, without heavy drug use.

Ladies, I’m sorry to say I don’t have a similar data-set to draw on for you. I can make some hasty guesses, but that’s all they’d be. One thing I can say for sure is that, proportionally, your limit is going to be less muscle for your frame. Instead of an FFMI of 25, yours might be down in the low 20s, and you’ll definitely have lesser measurements. It’s harder to give concrete measurements without more data, though.

A lot of people are operating under some major delusions – both in terms of what they can expect and in terms of how much muscle mass they actually hold. Unless you’ve spent some time trying to get really lean, you may not understand how much fat you’re actually holding. Fat likes to hide in strange places, and people have a habit of underestimating their true BF%. This isn’t helped at all by the fact that bodyfat measures are inherently inaccurate – the only way to get a specific number is through an autopsy. Anything else is at best a guess. Even DEXA and immersion testing have some substantial error involved.

Numbers like this are also a testament to the Good Bros out there that don’t think an opinion’s worth listening to unless you’ve gotten big and strong. Well, getting to the natural limit isn’t that tricky. If you want to talk about the really impressive results, then we have to talk drugs and genetic freaks. Which I’m all game to do, also; I’ve got no moral or ethical reasons to avoid drug discussions – but most people in the industry can’t say the same. Which is kinda the point.

Mainly I just want you to remember this anytime you hear people talk about “getting results”, and how you judge that in relation to the big boys up on stage.

2 thoughts on “Limits of Muscle Mass”

  1. Matt,

    Nice article. I ran into a thread at t-nation where the guys were respnding (yeah, negatively) to Casey Butt's calculations. Now, some had good intents and really sounded like they didn't want people looking for an easy out to not realize their full potential. That's all well and good, but the biggest crap-talkers were a bunch of goofs that didn't even figure the calculator correctly. I.E., they were counting their LBM as the highest weight the calculator was saying they could get to, or, estimating their current bodyfat at 10% when I'd bet upwards of 100 cyber dollars that they're nowhere near that.

    Anyway, good stuff, and glad to see you back at jpfitness.

    • Yeah, lots of guys don't like it, but between Casey's calculations (which are solid as far as I'm concerned) and the study on FFMI in users vs. non-users, it's a closed case as far as I see it.

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