Basal Metabolism Calculator

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Calculating your metabolism is the first step, and we also offer two calculators to help you know your lean body mass index as well as determine your muscle gain potential.

What is Basal Metabolism?

The basal metabolism represents the minimum energy your body needs to maintain vital functions at rest. Essentially, it’s the number of calories your body burns daily, even if you were lying down all day without moving.

Basal metabolism is a mechanism that varies significantly from person to person. To give you a precise idea, let’s take the example of two people weighing 80 kg: the first might have a basal metabolism of only 1400 calories, while the second could reach 5700 calories! This impressive difference is explained by several factors that we will detail.

Organs and Body Energy

Each organ in your body consumes a specific amount of energy, and the figures are surprising (when talking in kg below, it is not body weight, but organ weight):

• Your brain: 240 kcal per kg, (equivalent to a light meal, just to operate 1 kg of brain tissue!)
• Your heart: 440 kcal per kg
• Your liver: 440 kcal per Kg
• Your muscles: 13 kcal per kg
• Your adipose tissue: 4.5 kcal per kg

Here is a detailed table of your organs’ energy expenditure, based on the latest scientific studies. To illustrate, we have taken the example of a man 1.80m tall and 80kg (considered average) and a woman 1.65m tall and 60kg (corresponding to national averages).

Factors Influencing Your Metabolism

As explained, we are not all equal when it comes to our basal metabolism.

Body composition plays a major role;

at the same weight, a muscular person will have a higher metabolism than someone with more fat mass.

That’s why weight training, which allows for greater muscle mass, is an advantage, even during weight loss phases.

Age also influences your metabolism, with a decrease of 2 to 3% per decade after the age of 20. (Another reason to maintain your muscle mass!)

Genetic factors can vary your metabolism by up to 20% from one family to another, and studies even show variations of 500 kcal/day between different families.

Environmental factors. Certain lifestyle habits also affect basal metabolism, such as stress, smoking, coffee consumption, or fat-burning foods. Hyperactivity and even outside temperature, with cold leading to increased heat production by your body, thus boosting metabolism.

Gender is also a determinant: under equal conditions, men generally have a higher metabolism than women, mainly due to naturally higher muscle mass.

Finally, certain physiological conditions like thyroid activity can significantly impact your metabolism.

How to Calculate Your Basal Metabolism?

To calculate your basal metabolism, several scientifically validated methods are available to you, from the most precise to the most accessible. The Black method is among the most recent and seems particularly reliable for overweight individuals and seniors.

Calorimetry: The Most Accurate Method

If you want to know your basal metabolism very precisely, you will need to go to a laboratory for calorimetry. This technique measures the heat produced by your body and your oxygen consumption under very specific conditions: fasting for 12 hours, complete rest, in a room at 22°C.

So as you can imagine, this is not a free technique, and if you want ongoing monitoring, it can become costly.

Predictive Equations: The Best Compromise

Faced with this complexity, scientists passionate about bodybuilding have developed several mathematical formulas. Each has its peculiarities:

• The Harris-Benedict equation (1919): the pioneer, but which may now seem a bit outdated by new methods.
• The Mifflin-St Jeor⟧ formula (1990): a bit more precise, it has become the reference formula of the American Nutrition Academy
• The Black⟧ equation (1996): the most recent, which has the advantage of taking into account a broader and more diverse sample of possibilities.