Estimated reading time: 5 minutes

Everyone has different goals for increasing muscle mass. Some goals could be focused around reducing body fat percentage, preparing for bodybuilding competitions, or simply become stronger. Muscle mass is important for everyday physical functions such as walking. And, you know, lifting heavy furniture on moving day! 

All jokes aside, having enough muscle mass is part of living a healthy lifestyle. Let’s explore further what muscle mass means, as well as measuring muscle mass, and how to gain it. 

Woman building lean muscle mass in gym doing bicep curls on yoga mat

Muscle mass: defined

Muscle mass is exactly what the name suggests: the mass (size) of our muscles. Muscle mass forms part of lean body mass, which also includes our bones and bodily fluids. There are 3 different types of muscle: skeletal, smooth, and cardiac. Skeletal muscles take up about 30-40% of your body. Examples of these are shoulder, back, and thigh muscles. Cardiac muscles are located exclusively in the heart. Smooth muscles can be found within the gastrointestinal tract, organs, and skin, to name but a few.  

Muscle mass isn’t only important for weight loss and strength goals, but for your health too. For There are several medical diagnoses that require professional monitoring of muscle mass. Cancer patients are typically assessed for cachexia, which includes muscle wasting. Cachexic patients require special medical care and treatments to help with muscle mass and weight gain. Sarcopenia is when there is a decrease in the quality and quantity of skeletal muscle mass. Those with sarcopenia are at a higher risk for certain illnesses, fall risks, and decreased mobility. Sarcopenia is usually present in the elder population but can be present in younger adults too. 

How is muscle mass measured?

Measuring muscle mass requires specialized and expensive equipment. There are four types of equipment which include bioelectric impedance analysis (BIA), dual energy X-ray absorptiometry (DEXA), magnetic resonance imaging (MRI) and computerized tomography (CT) scans.  

MRIs, DEXA, and CT scans are typically used for diagnostic purposes in clinical and research settings. However, they are expensive and not easily accessible. Bioelectrical impedance analysis or BIA is probably the most cost effective and easiest way to measure body mass for personal interest. 

BIA measures body fat and muscle mass by measuring the rate of an electrical signal going through the body. Fat causes this signal to slow down. Lean body mass can be calculated using the data from BIA. There are other factors that are taken into consideration when using BIA as a measurement tool, these include: anthropometric measurements, gender, age, and even race and ethnicity. 

BIA is how smart scales and watches can accurately measure your body composition. 

How do you gain muscle mass?

When speaking about gaining muscle mass, it is usually in regards to skeletal muscle. There are many different exercises and types of physical activity that can help increase muscle mass. 

For each muscle in the body there are specific exercises that can be done to increase mass, whether they’re resistance, strength training, or cardio based.

In addition to strength training and resistance exercises, a diet that is rich in protein is usually beneficial in terms of gaining muscle mass.

What’s a good target to aim for?

Our bodies consist of fat mass and lean body mass. As mentioned above, muscle mass is only one element of lean body mass overall. As a result, there aren’t specific guidelines to follow in terms of muscle mass. 

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There was a study conducted over twenty years in Northern America that measured 468 muscle mass in both men and women. The study showed the differences in the age and sex of participants. Women had around 21kg of skeletal mass (~30.6%) and men had around 33kg  (~38.4%)of skeletal mass.

While this is a small representation of the population, its purpose was to give an idea of skeletal mass and was hoped to be used for comparison for further research. 

Black chalkboard of bicep muscle with steak, egg, cheese, nuts and other sources of protein inside it.

Since muscle mass doesn’t have any guidelines, body fat is typically used instead. 

Working backwards may give an idea of muscle mass. You can do this by figuring out body fat percentage first, subtracting the average skeletal mass, then calculating the remaining muscle mass. Theoretically, the lower the body fat percentage the higher the muscle mass. The American Council of Exercise (ACE) has a chart with body fat percentages but it does not include age or any other factors. It is simply based on men and women and their physical activity level.

 The Body Mass Index (BMI) is another calculation commonly used but it only takes body composition into consideration which includes fat, muscle, bones, and fluids. 

As always, it’s important to connect with a professional if you’re trying to change your body composition to meet certain targets. Goals and guidelines are all individualized, there is no one size fits all approach when it comes to muscle mass. 

Other things to consider

Around 50 years of age, muscle mass declines at a more steady pace. Women tend to lose about 0.5% of their muscle mass each year and men lose about 1% each year. There are many lifestyle changes that can help maintain or even gain muscle mass. 

These include but are not limited to: a well balanced diet, using a fitness watch to help track physical activity goals and body composition, and annual physicals with your healthcare provider to determine extra testing due to risk factors. 

Keep in mind that this is all dependent on your goals; if you are a bodybuilding competitor then your goals will differ from a middle aged female that is trying to minimize bone loss and reduce health risks.