This is an estimate of the amount of energy (in calories) your body needs on a daily basis, when it is at rest.
This value is particularly interesting because with your basic metabolism, you can then have an estimate of the energy your body needs according to your level of physical activity. This will allow you to compare your daily calorie intake to your daily calorie expenditure .
YOUR RESULTS
Your basal metabolic rate is awaiting calculation. Once calculated we will provide an immediate interpretation.
(which will allow you to use other formulas)
EXPLANATIONS
After performing the calculation (above) of your basal metabolism (BMR), you know how much energy your body expends daily when it is completely at rest. MB is therefore sometimes also referred to as resting energy expenditure (RRE). Yes, but here it is: your body is never completely at rest , the slightest physical and/or cerebral activity leads to an additional consumption of calories…
This is the reason why the table below (which we calculate for you automatically when you use our tool above), explains to you, in relation to your basal metabolic rate ( BMR ), what your real energy expenditure is.
| Your profile | Meaning | Your daily expense |
|---|---|---|
| Sedentary | Little or no daily exercise | MBx1.2 |
| Slightly active | You sometimes do physical exercises (1 to 3 times a week) | MB x 1.375 |
| Asset | You exercise regularly (3 to 5 times a week) | MB x 1.55 |
| Very active | You do sports or sustained physical exercise daily | MB x 1.725 |
| extremely active | Your work is extremely physical or you consider yourself a great sportsman | MBx1.9 |
The basic metabolism can therefore be understood as the “inevitable” needs of your body : it cannot function properly without this energy. This is the minimum energy the body needs to survive at rest , i.e. the energy required to ensure basic functions such as breathing, digestion, brain function, maintenance of body temperature…
Factors other than weight, height and gender can alter basal metabolic rate, including external factors. This is the case, for example, of climatic conditions: if it is particularly cold or excessively hot, then your body’s basic metabolism will be higher because your body will have to make additional efforts to “maintain” your system.
The good news is that exercising regularly increases lean body mass (i.e. the amount of muscle), and this lean mass consumes more calories than fat mass, even when the body is at rest . In other words, by having more muscles your body will consume more calories to function, even when you are not exercising. However, this change in basic metabolism takes place over the long term and we can therefore consider that the calories necessary for the body to function at rest are the same from one day to the next.
THE ENERGY BALANCE
Having an idea, even a rough idea, of what your body can consume on a daily basis can obviously help you better manage your diet . Because it is your diet that brings in the calories (which are then spent by your body): ideally, there should be a balance between your energy intake and your expenditure .
The body therefore functions as an energy balance and aims to expend the same number of calories as will be consumed. In this case the body weight does not change. But when the balance goes wrong there are then two scenarios:
If we eat more than we expend, we gain weight because we store the unused energy.
If we expend more energy than what our meals bring us, we lose weight, because the body draws on its energy reserves.
To lose weight, two solutions could thus be considered: eat less or increase physical activity . The first option would be possible, but to a limited extent because eating less than you need also means risking deficiencies in micronutrients which, as we have seen, are essential for metabolism and good health. There remains the solution that allows you to tip the scales in favor of weight loss without risking deficiencies: increase your physical activity!
ORIGINS OF BASAL METABOLISM
The basal metabolic rate derives from a formula communicated on October 8, 1918 to a scientific journal which published it in 1919 (1) . This reference formula is that of J. Arthur Harris (2) and Francis G. Benedict, following the analysis of 136 men, 103 women and 94 children in good health.
It is only valid in the range of 151cm to 201cm, for a weight necessarily between 25kg to 124.9kg and for an age ranging from 21 to 70 years old . The creators of this formula were aware that, for the elderly, reliability could sometimes be called into question. This is the reason why Harris and Benedict carried out new research and made publications in 1928, then 1935, but without modifying their original formula.
Harris and Benedict formula (1919):
In 1984, Roza and Shizgal proposed an improved formula (3) from that of Harris and Benedict. This is the formula we use in our calculator, except for people who are overweight or over 60 years old (in which case we automatically switch to Black’s formula, below) . In their publication Roza and Shizgal specify that the formula of Harris and Benedict makes it possible to obtain an estimate of the basal metabolic rate with an accuracy of around 14% for a person in “good health” and “properly nourished”. However, for people suffering from malnutrition, the formula is not reliable. This is therefore improved as follows:
Harris and Benedict’s improved formula by Roza and Shizgal (1984):
For the elderly and overweight people, the formula of Black et al, which appeared in 1996 (4) , is used. It is based on larger samples and more recent analyses:
Black et al (1996) formula:
In addition, Black, through this study, also specifies that the limits of the human body in terms of daily energy needs seem to be:
- At least to expend 1.2 times basal metabolism per day (sedentary person)
- At most to spend 4.5 times the basic metabolism (elite of the most enduring high level athletes)