Action 2: Case Study

Have you ever thanked your body for all the work it does for you, even when you are sleeping?

When you are completely still your body is working to keep you alive because you are constantly burning calories without even moving. Your body is an amazing vessel, it needs energy to function and for it to work efficiently it needs to fuel your respiratory and circulatory organs, neural system, liver, kidneys, fascial network, muscles, bone, and everything in between. That’s a tall order to fill.

Every human being is different, the amount of energy it takes for me to be me is different to you. There is a balance of energy intake and energy expenditure within our bodies and to calculate this we use the Basal Metabolic Rate (BMR).

BMR is defined as the energy required for performing vital body functions at rest. It is an important calculation to help with weight related and lifestyle interventions as we can estimate and compare an individuals BMR to their total daily energy expenditure and adjust or adapt accordingly. An accurate estimation on an individual’s BMR can immensely influence lifestyle strategies and obesity prevention. It is a very well-known formula and an important one to understand.

You use approximately 70% of daily calorie consumption for your basal metabolism. Couple that with the added energy you need to perform activities such as movement and you are burning a lot of calories throughout the day and the more vigorous and dynamic the activity, the more you lose. The reason why you burn more with movement is because your skeletal system acts as a metabolic engine and greatly affects your BMR, and the more muscle mass you have the more fuel is required. Accounting for approximately 40% of your body weight you can understand why this uses a large amount of energy and why it influences your BMR significantly.

How do you calculate your BMR?

The standard and basic way to calculate your BMR is by using an equation of weight and age. However, we now know there is a lot more to it than that.

Tanita have conducted in-depth research for many years on the relationship between BMR and Body Composition which they have found gives a more accurate and individualised reading when using an impedance measurement (a bioelectrical method for measuring body composition based of an electrical current that travels through your body).

Case study

What are your first thoughts when you think of a sumo wrestler? Do you think they are healthy?

Fun fact: most are. BMI alone states that they are obese but did you know that there are more variables to look at that can determine health?

Following this, their body fat percentage mostly falls within a healthy range and their fat is stored as subcutaneous fat (under the skin) rather than visceral fat (within the abdominal cavity).

Now jump to the other end of the spectrum. What are your first thoughts when you think of a bodybuilder? Big muscles? Super low body fat? Right, well some professional bodybuilders actually reach body fat percentages as low as 3%, anything lower and the body physically struggles to survive. But if you take a look at the BMI of a bodybuilder it states they are obese! How can you be classed as obese if you have very low levels of body fat and the World Health Organisation (WHO) defines obesity as having excessive fat accumulations that may impair health?

BMI is calculated using your weight and your height, with no consideration for what your weight is made of. Just by diving a little deeper into these two above examples it is clear to see that BMI does not truly reflect your ‘health’ status and other factors need to be considered and explored to truly understand your body.

Now knowing that the only two factors that affect BMI are height and weight, which of these two individuals will have more variability in their BMI within the next 5 years?

Let me just add this information: on average females are in their peak growing phase between 11.5 years old and 14 years old.