Lean Body Mass, Muscle Mass, and Muscle Percentage

Ever wonder what all that fitness jargon means? Me too.

If you want to learn how to calculate your Lean Body Mass, click here. I wrote a post about calculating Lean Body Mass and your ideal weight a few days ago.

Now onto the question of muscle mass. It seems obvious that muscle mass is the amount of muscle present in your body, and that a muscle percentage statistic would show you the percentage of your body that muscle mass takes up. From all of the googling I've done, this seems to be the case, but when you pose the question of calculating these numbers, they don't tend to agree!

Let me explain. I just bought a body composition scale. In fact, I bought this one:

It's a Beurer Body Analysis Scale.

Anyway, some scales measure muscle mass and some scales measure muscle percentage. Mine measures muscle percentage. I have also used a scale that measures muscle mass. Here's where it can get confusing. I googled how to calculate muscle mass, and instead the few websites I found seemed to be giving me a formula for calculating lean body mass, which I already know how to calculate (see previous post). The formulas would use your body fat percentage and simply figure out what your supposed muscle mass is by subtracting your BF% from your total weight... but that leaves all the other stuff in your body in that number as well like bones, veins, and whatever else is in there. Then, somehow, I got a number that seemed close to what a previous scale had given me for muscle mass, but it seemed wrong too because if you took my body fat mass and my supposed muscle mass and added them together, there were only about 4 lbs left over to account for bones and stuff. I'm no expert, but I'm pretty sure that all the bones in my body probably weigh more than 4 lbs.

So I'm still lost, unfortunately. If anyone can explain to me how these scales measure muscle mass vs muscle percentage, that would be awesome. If it's exactly what it sounds like and the 2 scales that measured the 2 different statistics on me are just miles apart with regard to accuracy, I can understand that too.

I think that the closest I've gotten to a real muscle mass is actually by using the muscle percentage provided by the scale I own. This number seems to take into account my body fat percentage while also leaving out bones, blood and vessels, and non-muscle organs like skin. If my scale is reasonably correct, my muscle% is 29.4% or right around 51 lbs of muscle.

Healthy Weight Loss and Your Ideal Weight

One of the first things a person thinks about after deciding that they want to lose weight is how much they want to lose, or what their goal weight should be, and many people don't know how to calculate that properly.

Personally, I just guessed.  I asked my doctor what a healthy weight range for my height would be (between 125 and 155 lbs) and then just kind of picked an arbitrary number somewhere in the middle (140 lbs).  My original method could work, but everyone is unique, even if you're the same height as someone else.  Where another woman my height could easily maintain a healthy weight of 125 lbs, I think I would look sick if I lost that much weight.  So how do we figure out what our ideal weight is?

Well, I've discovered a website: BuiltLean.com.  Marc Perry has some great articles on his website that you can access even if you don't subscribe to his program.  I found one on how to calculate your ideal weight. (source article)


So Marc Perry has a formula for calculating your ideal weight:

Lean Body Mass / (1 - your desired Body Fat Percentage in decimal form)

The formula in a simplified form looks like this:

LBM / (1 - your desired BF%)

Okay, I know what you're thinking.  What the hell is Lean Body Mass?!  Lean Body Mass is everything in your body (muscle, organs, bones, tissue, blood vessels, etc) except fat.

But how do you figure out that number?  Here's how:

LBM = Your Current Body Weight - (Your Current Body Weight x Your Current Body Fat Percentage)

I know, I know, so many numbers!  And how do you know what your body fat percentage is?  Here's another number you need to know and keep track of.  

You can figure out your body fat percentage a couple different ways.  You can buy a scale that measures certain statistics about your body including your body fat percentage, your muscle mass, your bone mass, etc.  These scales can range in price from just under $100 to over $400.  I'm looking to purchase one that's about $220 after researching and reading tons of reviews.  Another way you can measure your BF% is by using a caliper which is much cheaper to buy, although it can be difficult to use if your body fat is over a certain range.  Currently, my BF% is higher than the range ideal for using a body fat caliper which is why I'm looking to buy a scale.

Anyway, back to the formulas!  I have a number for my BF% because of my brief stint on Herbalife.  The coach I spoke with had a fancy scale like the one I'm looking to buy and so I got a baseline for my stats.  I want to give you an example so you can see how it all works with real numbers.  I'll use my numbers.

First let's calculate my lean body mass.  Remember, LBM = CW - (CW x CBF%)

My current weight is 176 lbs.  The last time it was measured on the fancy scale with Herbalife, my BF% was 41.5%.  We have to convert that percentage to a decimal, so my formula will look like this:

176 - (176 x 0.415) = 102.96 = LBM

So my lean body mass is ~103 lbs.  Now to calculate my ideal body weight.  Remember, Ideal Body Weight = LBM / (1 - your desired BF%). (For more information on your ideal body fat percentage, visit this link or this link.)

My Ideal Body Weight = 102.96 / (1 - 0.225) = 132.85

My ideal body weight is somewhere between 132 and 133 lbs.  Because I know this is going to be a difficult goal to reach, my goal weight range is between 130 and 135 lbs.  I'm giving myself some leeway. What's interesting is that I was ~130 lbs all through high school, and when I first got myself into shape in college, I weighed 135 lbs.  It's nice to know that this weight range is realistic for me.