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Muscle Mass Matters – How Body Composition Influences Health

For most people/athletes/coaches/ training enthusiasts reading this, it’s safe to assume that at some point in your training, improving body composition (the ratio of lean muscle mass to fat mass), was a primary focus. While the importance of lean muscle may seem obvious, just how important is it for health purposes? To what extent can we see some reasonable improvements in their markers by improving how big their biceps or glutes are? How much fat keeps us healthy and how much makes us unhealthy?

Plenty of questions; let’s see if we can find some answers!
When it comes to seeing if your body composition is healthy/unhealthy, a simple measurement that most doctors use (as the first piece of evidence gathering) is called your Body Mass Index (BMI). 

Your BMI is based on a calculation using your height and weight. It’s very simple actually, just take your weight in kilograms and divide it by the square of your height in metres (BMI = kg/m^2).

While many people critique this method, we think that is misguided. Of course, BMI isn’t perfect, but a simple calculation — using only your height and weight — can tell you a lot about your health (though, admittedly, not everything). For example, ‘normal’ ranges are associated with a lower risk of death.

According to the Australian Government, these are the classes of BMI: 

  • Below 18.5 – underweight range
  • Between 18.5 and 24.9 – you’re in the healthy weight range
  • Between 25 & 29.9 – you’re in the overweight range
  • Between 30 & 39.9 – you’re in the obese range

Now, as we said, there is a little bit of an issue with the use of BMI… and we shall explain that for you now.

You see, a lot of us are quite different. Short and thick, tall and thin and everything else in between. You can have short, muscular individuals who would be placed in higher BMI categories even if they’re relatively “healthy,” just like you can have individuals who fall into lower BMI categories with poor body compositions (high fat, low muscle). To the naked eye and to the BMI calculator, health can look very different. 

That is why a full appreciation of the situation is needed — not just one or the other. While BMI can be used as a general indicator, it probably isn’t the most accurate determinant of how healthy you really are, especially if you are extreme in your body composition (excessive muscle or fat).

Abramowitz et al (2018) actually conducted a cohort study on 11,687 participants and took this fact into account, including both BMI ratings and a more specific measure of an individual’s fat mass and muscle mass ratio (using a DEXA scan). They wanted to see if the amount of muscle mass influenced health and mortality. Surprise, surprise, it looks like it does (shocker, I know).

What they found was particularly interesting – your risk of death was lower in almost all BMI categories if you had a certain level of muscle mass!

Abramowitz et al (2018)

To give you an idea of what the graph shows above, what we see is a higher risk in the lower BMI category (18.5- <22) since on average they have lower amounts of muscle mass. This means that, while being overweight is no-good, even being underweight is a risk factor! Or, what this really translates to Being under-muscled is a risk factor.

Then, as we move up the categories, those who were able to hold on to muscle mass ended up having a lower risk of health concerns. If we look at the categories with high fat mass and low muscle mass, then we can see how their risk increases rapidly. Muscle is your organic armour folks!

But why exactly is this magnificent muscle mass so important? What are the actual benefits of building some busting biceps or glorious glutes? 

To demonstrate this, Maestroni et al. (2020) brought out an absolute pearler of a paper, going into the details of how resistance training and building muscle can result in some mighty fine health benefits.

Here is a general outline of what the review looked into:

  • Improvements in body composition meant decreasing general systemic inflammation and reducing the likelihood of developing diabetes or heart disease.
  • Improvements in glucose uptake into the muscle. More muscle equals greater glucose storage capacity and blood-glucose control.
  • Increases mitochondrial density and oxidative capacity. This improves the ability to oxidise both glucose and fat for energy.
  • Reduction in anxiety and depression.
  • Improvements in sleep quality.
  • When combined with aerobic exercise, it can further improve cardiovascular health.
  • Improve cartilage, tendon and bone health.
  • Lot’s more, just check the image below, or better yet check out the paper for yourself!

Maestroni et al. (2020)

These are some amazing benefits, however, above becomes increasingly more important for those with disease and older individuals. 

To expand on this, resistance training and muscle accretion is seen as critical for Type II diabetics (Pesta et al., 2017). It is expected that within the next 20 years, we will have a mammoth 600 million people worldwide suffering from this disease. This is a concern as diabetes brings with it a whole host of additional risk factors including hypertension and cardiovascular disease. Because of this, just hitting the recommended minimum for aerobic and resistance training in a week, serious improvements can be realised in populations of this kind.

Another population that falls into this category would be aging individuals. Often older adults don’t participate in resistance training as they feel too frail to do so, however, they are some of the most benefited individuals by exercise of this kind. Older individuals can combat age related muscle loss (sarcopenia) by including a well-tailored plan that focuses on building some muscle, and with that, enjoy the host of benefits we’ve discussed that muscle has (Faulkner et al (2007). We also see some pretty decent quality of life gains for much older (80+) populations even with low volume and overall short sessions (Grgic et al. 2020)

So regardless of age, we can all reap the benefits!

While we see some obvious improvements by increasing muscle mass, how does the amount of body fat we carry impact our health? Australia is slowly following it’s first-world-country counterparts in the progressive increase of overweight or obese individuals. In a survey completed throughout 2017-18, 67.0% of Australian adults were overweight or obese, which is approximately 12.5 million people (ABS 2018)

That’s two-thirds of Australia….2 in 3 people are now overweight or obese! 

This a growing issues as we see trends in the literature showing how being overweight or obese does put you at a higher risk of health complications down the line. In a review by Gruzdeva et al (2018) we see obesity as one of the leading risk factors for the development of Coronary Artery Disease (CAD) and Type II Diabetes. 

While we do see associations between BMI and increased risk factors, it seems like where the body fat is stored plays a more specific role in the predictability of future health complications. Elffers et al (2017) explains this in her paper discussing how increased visceral fat (fat around organs) is highly linked to cardiovascular risk factors (in women. The study didn’t find significant results in men). 

But this begs the question, can we really be healthy even with a little extra padding? I’m sure most of you have heard the notion of Health At Every Size (HAES) – the idea that we can be overweight/obese, but still be within what is defined as metabolically healthy. Is this truly the case?

Well, a meta-analysis by Lin et al (2017) showed that in a group of obese individuals, about 35% of them were deemed “metabollically healthy obese.” So it seems reasonable to suggest that we can indeed be healthy while holding on to a little more fat. But, like most things in the health & fitness realm, it’s not that simple.

It turns out that those who were metabolically-healthy and obese, had an 80% higher chance of showing abnormal metabolic findings when compared to those with “healthy” BMI’s over time.

When they did follow up with individuals (across 3-10 years), they recorded that 49% of them did end up becoming metabolically unhealthy. So while the original finding showed that metabolically healthy and obsese is possible; it only seems possible for a period of time. And as we have covered so far, our goal is to maximise health over long periods of time.

However, let’s remember that the point of the above information is not to stigmatise, but rather to inform. I would certainly recommend the work of Dr Gabrielle Fundaro & Shannon Beer if you would like to dive a little deeper into the rabbit-hole of stigma, psychology and mindfulness with regards to weight.

To conclude, general improvements in body composition have demonstrated positive benefits across the board and should be a consideration in any health-focused plan; especially for those participating in sports where the increase in body fat isn’t regarded as a concern, and as such, isn’t restrained to the same extent — *cough* I’m looking at you, powerlifters.


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