Muscle Matters

Go to any health coach, personal trainer, or nutritionist and you won’t have any problem finding out how much body fat you should have. We are so focused on fat loss that even though many professionals understand the importance of muscle mass, no one has figured out a recommendation for it. Let’s see if we can remedy that situation.

Muscle mass is important for a number of reasons. It’s what allows us to move our bodies. It provides protection against stress. Muscle improves our metabolic health and helps regulate our hormones. The amount of muscle you have is an indicator of how healthy you are.

“Muscle is perhaps the most important organ system as it relates to combatting our current health crisis, regaining exceptional health, and maximizing physical performance. Muscle is even more important as we age yet is often the most overlooked, even by modern-day medical practices. Muscle is fast becoming the 6th vital sign.”

Dr. Gabrielle Lyon

How Much does Muscle Matter?

“A substantial proportion of MetS (metabolic syndrome) cases would have been theoretically prevented if prior exposure to low muscle mass and strength were eradicated… Findings indicate that insulin resistance is a central abnormality in the MetS and that muscle mass and strength are strong protective factors independent of insulin resistance and abdominal fat accumulation.” – Inverse associations between muscle mass, strength, and the metabolic syndrome 

“All four outcomes decreased from the lowest quartile to the highest quartile of skeletal muscle index (SMI), the ratio of total skeletal muscle mass (estimated by bioelectrical impedance) to total body weight…Across the full range, higher muscle mass (relative to body size) is associated with better insulin sensitivity and lower risk of PDM (Diabetes Mellitus)” –  Relative muscle mass is inversely associated with insulin resistance and prediabetes

The Pathogenesis of Sarcopenia

“The pathogenesis of sarcopenia and CVDs (Cardiovascular Disease). Malnutrition, physical inactivity, insulin resistance, inflammation, hormonal changes, autophagy, apoptosis and oxidative stress are involved in the occurrence of CVDs and sarcopenia. Sarcopenia is closely related to cardiovascular disease, which affects each other’s course of disease. In addition, CVDs aggravates the adverse outcomes of sarcopenia, including falls, fracture, frailty, cachexia, hospitalization and mortality. At the same time, the prevalence of CVDs in sarcopenia patients is significantly increased, such as HF, hypertension, atherosclerosis and CHD.” – Relationship Between Sarcopenia and Cardiovascular Diseases in the Elderly: An Overview

The Fat Standard

Body fat % is the go-to for most people when they start trying to get healthy. It is a common metric that aligns with the idea that weight loss is the key to being healthy. Except that it’s not.

The amount of body fat a person carries is a symptom of an inefficient and improperly managed metabolism. There are two main things that create conditions of poor metabolic performance and the accumulation of body fat.

  1. Not getting enough Nutrient-Dense, Bioavailable, and Satiating food
  2. Not doing activities that stimulate muscle growth and improve metabolic performance

Of course, it’s a lot more complicated than that right? Not really.

Not eating food to optimize your health means you’re eating foods that do the opposite. Every bite you take is adding to your metabolic dysfunction. This is where you start to gain body fat. 

Guess what else poor nutrition does, it limits your ability to gain and maintain muscle mass. So you end up with more fat AND less muscle.

Living a sedentary lifestyle with little to no movement and stimulation of muscle is a clear path to metabolic problems. Muscle burns fuel, muscle utilized protein, muscles are the engine that everything you eat is meant to support. If you aren’t moving your body, there’s nowhere for all that food to go, nothing is asking for it. The only place your body can put it is in your body fat.

Muscles need activity in order to grow. Your body responds well to being used, not to sitting still. When you use your muscles they respond by growing and developing to provide the strength and ability to support what you’re asking them to do. If movement is life, you can’t have much of one without adequate muscle mass.

Even though the standard of improving health that many people default to, is losing body fat, you can see that’s not really the problem. The issue is most people are under-muscled.

Body Fat % Recommendation Problems

Common body fat recommendations have a couple of issues. First, they are too broad. In an effort to “cover the bases” most organizations have provided ranges that allow them to meet the obligation of offering guidance without the risk of being wrong because they were too specific. Secondly, they are mostly based on recorded averages from the current population, not evaluated based on a level that indicates optimal health.

Common body fat % recommendations look like this. 

There is a giant range based on health, age, and gender. This is bogus. If the idea of making a recommendation is to provide an individual with a target for improving their health, how is this helpful? Additionally, and I am very passionate about this….. Body fat % does not need to increase with age. Period, end of the story.

When you dig into the data and how health organizations come up with these recommendations, you find that they are simply percentiles of the general population. Since the general population is obese and unhealthy, I’m not sure we should be basing our body fat % goals on that control group.

Lastly and this is a bonus point. Body Mass Index (BMI) is still king in the health and medical industry. Many of the recommendations and information out there rely on body fat as it compares to BMI and doesn’t consider the role that muscle mass plays in the equation.

Ref. Article: Say Goodbye to BMI

Body Fat % in Context

Let’s set a baseline before we get into the meat of this.

Optimal health is the goal. That means being fit, NOT being skinny. When I talk about losing body fat, I’m talking about what happens as a result of improving your metabolism and increasing your muscle mass. This is not a recommendation on how to be skinny.

The following recommendation is what I consider an ideal body fat % that indicates optimal health. 

Is it exactly the same for everyone? Absolutely not. Do I think it’s a good target for everyone to shoot for? Absolutely.

Body Fat % Recommendations

BF% for Men (All ages)

  •  20% or less

BF% for Women (All ages)

  •  23% or less

These percentages are a combination of clinical experience and information recorded on populations that have a higher average level of fitness than the general population. If the goal is optimal health, then targeting averages based on unhealthy people is counter-productive.

Now that we’ve worked through that, let’s dig into the really important stuff.

Fix your muscle. Fix your health.

There are 3 main components to your body composition. They are usually presented as follows.

  1. Lean Body Mass (lbs)
  2. Body Fat %
  3. Skeletal Muscle Mass (lbs)

Lean Body Mass is how much your body weighs minus body fat. Body Fat % is the amount of body fat in pounds divided by your total weight. Skeletal Muscle Mass is how much muscle (specifically muscle attached to bone, it does not include organ muscles) you have in pounds.

Check this study out. Relative Lean Body Mass and Waist Circumference for the Identification of Metabolic Syndrome in the Korean General Population

In this study, they took data from almost 500,000 people and used it to determine what the cutoff was for the lowest amount of lean mass someone could have before they indicated that they were metabolically unhealthy. 

What they found within this population was the cut-offs of Relative Lean Body Mass for predicting metabolic syndrome were 74.9% in males and 66.4% in females.

While it’s great to have an idea of how much lean mass would be good to shoot for, overall lean mass isn’t that easy to manipulate. Luckily, Skeletal Muscle Mass is one very specific component to overall lean body mass that you can change and control very well.

What is Skeletal Muscle Mass Percentage (SMM) %?

Many body composition reports tend to overlook the percentage of skeletal muscle compared to the overall weight, even though it’s a more impactful metric than body fat % is.

If you weigh 150lbs. and your body fat % is 30%, you have 45 lbs of fat. If your skeletal muscle mass is 70lbs you have SMM% of 46%.

I found references to 13 different studies that used calculations for SMM% to define the lower limits of skeletal muscle mass that indicates sarcopenia (an unhealthy low level of muscle mass) in adults. The overall average across these studies is 31.7% for men and 26.3% for women.

Reference Values for Skeletal Muscle Mass – Current Concepts and Methodological Considerations

Here’s where the fun begins. In the 10+ years I have been a fitness coach, I have never seen any industry, health, or fitness organization publish a recommendation for SMM%. I have looked, and the only thing I have found is the recorded averages of the general population.

Here is an example from Omron, one of the largest sellers of body composition products on the market. This is information they published based on users of their scales.

According to this dataset, the average man is about 35% SMM, and the average woman is 32% SMM. This is only 2.3% higher than the lowest range of defined sarcopenia in men and 5.7% higher for women. 

Taking this information into consideration, I looked at people that I consider healthy and fit. That is the goal, right? I looked at data from clients I’ve worked with, other people in the health and fitness community, and even myself, to determine a realistic recommendation that makes sense. I asked two basic questions. 1. Can normal people set it as a health goal? 2. Is it realistic to expect people to get there?

Remember, optimal health is the goal. That means being fit and physically capable. The following recommendation is what I consider an ideal SMM% that indicates optimal health. 

Is it exactly the same for everyone? Absolutely not. Do I think it’s a good target for everyone to shoot for? Absolutely.

Skeletal Muscle Mass % Recommendations

SMM% For Men (All ages)

  • 45% or more

SMM% For Women (All ages)

  • 40% or more

You can see this is higher than the Omron “normal” numbers. However, it is lower than many of the references I used in the comparison of “fit” people. My SMM % for example is 51%. Looking at the OMRON numbers again, we see on the ”++(very high)” (the fittest individuals), the median is 49% for men and 45% for women.

In context, these recommendations would mean a 150lbs woman should have 60lbs of SMM and a 200lbs man should have 90lbs of SMM.

These are solid targets that you can use to help improve your metabolic health. If you change your focus to growing muscle, you will see an overall improvement in your quality of life, physical ability, energy levels, and body fat loss.

Article Ref: Fat Loss is Dead

Now What?

Do you know what your body composition is? If you haven’t had an opportunity to get a body scan, I highly recommend it. My go-to device is from InBody USA. I trust the accuracy and consistent performance of InBody devices so much that I used one for all my members when I owned my CrossFit gym and I have my own at home. Many other fitness centers and supplement shops have a commercial-grade InBody scale that you can use. If you want something more convenient, you can get an at-home product here, At Home InBody Devices.

Here’s a sample of what you can get from an InBody device sitting in your bathroom.

As you can see, it provides all the information you need to understand exactly where your body composition is and where you need to focus. Using this information gives you the power to identify a goal that will help you improve your health. Here are three things you can do to start improving your SMM%

  1. Eat more protein, your body needs it to grow
  2. Move more weight, you need to give your body a reason to grow
  3. Get more sleep, your body needs time to grow

Video Ref: What’s it take to build Muscle?

That’s the basics.

I cover a whole lot more about how to improve your metabolic health, gain muscle, and get started with fitness in my other blogs, and videos at Get Fit With Coach Bronson


American College of Sports Medicine, Body Fat % of adults in law enforcement https://www.acsm.org/docs/default-source/publications-files/getp10_tables-4-4-4-5-updated.pdf 

What is Skeletal Muscle


Omron FAQ


Body Fat Percentage Charts


Healthy percentage body fat ranges: an approach for developing guidelines based on body mass index


Study on body composition and its correlation with obesity


Optimal Body Fat Percentage Cut-Off Values in Predicting the Obesity-Related Cardiovascular Risk Factors: A Cross-Sectional Cohort Study


Relative Lean Body Mass and Waist Circumference for the Identification of Metabolic Syndrome in the Korean General Population


Relationship Between Sarcopenia and Cardiovascular Diseases in the Elderly: An Overview


Sarcopenia exacerbates obesity-associated insulin resistance and dysglycemia: findings from the National Health and Nutrition Examination Survey III


Relative muscle mass is inversely associated with insulin resistance and prediabetes. Findings from the third National Health and Nutrition Examination Survey


Inverse associations between muscle mass, strength, and the metabolic syndrome


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