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TnT Metabolic Igniters

Body Composition- What is it & How to Measure it

What is Body Composition?

Body composition refers to the make-up of the body. To simplify and measure body composition, we often divide the human body into two components, lean body mass (fat-free mass) and fat mass (adipose tissue). 

Lean Body Mass(aka fat-free mass) refers to the combined mass of our muscles, connective tissues, bones, organs, and blood. Improving our body’s proportion of fat-free mass can significantly improve our health and well-being. The American College of Sports Medicine explained that the healthy range of fat-free mass in females is 68-80%, and in males is 78-90%.

Muscle Mass Percentage refers to the percentage of your total weight that is comprised of just your muscles (excludes bones, organs and fat mass). Since muscles are more metabolically active (i.e. they burn more calories) than fat mass, having a higher percentage of muscle mass contributes to healthy weight management. From a dietary standpoint it is important to have appropriate amounts of protein to sustain the activity of your muscles, including muscle growth and recovery.

Fat Mass refers to the portion of our body mass that is comprised of adipose (fat) tissue, and is often expressed as a percentage of our total body mass. The human body needs fat for insulation, to protect vital organs, and to maintain body function. According to the American Council on Exercise, it is essential for females to have 10-13% body fat in order to sustain body function, and 25-31% body fat is considered to be ‘acceptable’. For males2-5% body fat is essential, and 18-24% is considered ‘acceptable’. Overall, body fat percentages can indicate your susceptibility to weight-related health risks, which are heightened when fat mass percentages are too high or too low. Adipose tissue can be divided into two types, visceral and subcutaneous.

Visceral Fat is found in the deep abdominal,. It is the fat that surrounds our vital organs. Visceral fat can be dangerous and it is associated with negative health consequences. It is promising to note that visceral fat levels are modifiable, and can be lowered with appropriate cardiovascular exercise. 

Subcutaneous Fat is the other type of fat that we have. This is the adipose tissue that lays just below our skin layer (not surrounding our organs). It does not pose as much of a health concern as our visceral fat levels, nevertheless it still contributes to our overall proportion of fat mass, which we want to keep in check.


It is interesting to note that on average, body fat doubles between the ages of 20-65. Additionally, muscular strength (which influences lean muscle mass) is typically then it decreases by 5-10% per decade after the age of 45.


How to Evaluate Body Composition

There are a number of tools that measure body composition, however, not all tools are equal. Regardless, it is beneficial to use the same measuring tool overtime in order to accurately track changes related to body composition. Some of the drawbacks and benefits of common body composition measuring tools/devices/protocols are explained here:  

  • Body Mass Index (BMI) takes into accounts one’s height when analyzing total body weight. This is a popular measure (especially in the health care system) that is used to quickly identify if someone is at risk of weight-related health problems, such as heart disease, high blood pressure and diabetes. 

‘Normal’ BMI, where an individual is not at risk of health problems, ranges between 18.5-24.9. It is important to note that BMI predicts one’s body composition, but it doesn’t measure it directly. As such, BMI does not distinguish between fat mass and muscle mass. Accordingly, a person’s BMI won’t change if s/he experiences a concurrent, and proportional, decrease in fat mass and increase lean body mass.

Correspondingly, BMI values often overestimate  fat mass (resulting in a higher BMI) in those who are very muscular or who have larger frames, as it doesn’t accurately account for the weight of their muscles and bones. Additionally, BMI scores often underestimates fat mass (lower BMI) with older adults (i.e. those who have lower levels of lean body mass). As such, BMI is considered to be less accurate than many of the other measures.

  • Circumferences (Girth) & Scale Measures are another relatively quick measure that is often used to predict one’s risk of experiencing health problems. Circumference measures specifically, provide good indication of changes in one’s body dimensions, however, they do not distinguish between lean body mass and fat mass. Nevertheless, using circumference and body weight measures in combination, can be a fast and motivating way to track changes in your body. When taking circumference measurements, make sure you are consistent with the locations (anatomical landmarks) that are measured. The results from these measures can be plugged into a predictive equation to estimate body fat percentage.
    • Note:Bodyweight can fluctuate approximates 4-5lbs in a given day, for the average adult.scale-2
  • Bioelectrical Impedance (BIA) scales measure your body’s proportions of lean and fat mass by sending a harmless current through your body and timing how long it takes to return. This rapid process calculates your weight, body mass index (BMI), lean body mass and body fat percentage, which provides a better understanding of where you rank compared to the healthy recommendations. Body composition measurements are used to indicate if you are at risk of health problems, such as diabetes, sleep disorders, heart disease, certain types of cancer, and arthritis.
  • Skinfold Measurements are a very good, valid, way to measure subcutaneous adipose tissue. Skinfold measures are taken at specific anatomical landmarks on the body (usually dependent on gender), where a practitioner will draw the skin and subcutaneous fat away from the muscle and measure it using skinfold callipers. The sum of these measures can then be used to calculate a person’s body fat percentage. A drawback of this measurement technique is that some people may find it uncomfortable (invasive) to have a fitness and/or medical professional measure the skinfold sites. Additionally, there is a 6-8% potential margin of error depending on the experience of the practitioner and his/her familiarity with this body composition measurement protocol. 


Improving your Body Composition

To improve body composition, it is essential to take into account both diet and exercise. Keeping a food log that includes your emotions when you eat, what and how much you eat, and what time of day you eat can be very beneficial. Try to keep a balanced diet of fruits & vegetables, meats & alternatives, milk & alternatives, and grains. For more information ask your doctor, consult the Canadian Food Guide, and/or seek advice from a dietitian. 

Exercise programs that are aimed at improving your body composition should incorporate both strength training and aerobic conditioning work. Improving both of these fitness aspects will help to increase muscle mass and decrease fat mass. Interestingly, exercise doesn’t only increase the number of calories you expend, but it may also suppress your appetite.


Final Reminders

Change takes time, so don’t let the numbers discourage you. In fact, the American Council on Exercise recommends only reassessing body composition on a quarterly basis. Therefore, even if you don’t see a change in your body composition right after improving your nutrition and exercise habits, take notice of other changes that are occurring. Perhaps you have improved energy levels, are able to fall asleep easier, notice that your clothes fit differently, have a more stable mood throughout the day, feel fuller for longer, experience less daily pain, and/or have improved function when performing daily tasks. These more ‘subjective’ changes could be more important than the ‘objective’ body composition values.



Nieman, D. (2011). Exercise testing and prescription: A health-related approach seventh edition. New York: McGraw-Hill

Renee, J. (n.d.). What is fat-free body mass. Retrieved from

Spivey, K. (2014). Physiological assessments. In Bryant, C, Jo, S., Green, D. (Eds.), American Council on Exercise personal trainer manual fifth edition(pp. 149-260). 

  • reply
    Bodyscan Ltd
    October 11, 2019

    Great source of information about body composition on how to measure it. Thanks for sharing your precious knowledge to improve our body composition.


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