Our bodies use energy to function. This total energy used is called Total Energy Expenditure (TEE). You’ll also find it termed as Total Daily Energy Expenditure (TDEE).
Energy is expressed in Joules and Kilojoules (Kj) or Calories / Kilocalories. While a kilojoule refers to 1000 joules, both calories and kilocalories are the same at 1 calorie. The joule is named after James Prescott Joule.
What is BMR?1
Of the TEE, the biggest component is the Basal Metabolic Rate or BMR, accounting for 50% to 75% of the TEE, and is measured under standardised conditions, such as:
- state of wakefulness of the subject
- in a given position
- in a certain physical state
- and a certain mental state
- at a certain environmental temperature etc.
BMR is the amount of energy burned by the body in the conditions mentioned above. Under some conditions, BMR can also be equated to RMR (Resting Metabolic Rate).
There’s also the energy we burn during routine, recreational and other physical activities. So our real daily metabolic burn will likely be higher with the energy expenditure of those activities factored in. BMR is a component of our total energy expenditure, remember?
The other significant use of energy in our bodies, other than the metabolic burn and the energy used for physical activities, is the energy our bodies use to generate heat, or Thermogenesis.
Roughly speaking, for a sedentary woman with a body weight of 60 kilos, the primary components and their approximate use of energy is as follows. There are other components too, which I won’t get into in this article.
- Basal Metabolic Rate: 70%
- Thermogenesis: 10 – 15%
- Physical Activity: 15 – 20%
BMR depends on the following factors:
- Body Size
- Body Composition
- Genetic Factors
- Physiological Status
- Hormonal Status
Equations exist that approximate all of the variables that go into the measurement of BMR, including those related to the body and those of the environment among others. These equations include the Harris Benedict and Mifflin St. Jeor equations.
The input these equations require is usually age, gender, body weight and height, and the usual output is estimated BMR in calories.
Why is BMR important?
At one level, eating less than our BMR results in weight loss and more, in weight gain.
Weight balance however isn’t just as simple as that, as there are many more considerations such as hormones, frequency of meals, genetic make up, environmental and psychological considerations, source of calories etc.
Use the form below to calculate your BMR.
BMR is a measure of the largest component of our body’s use of energy. It is important as it is the base variable in the context of weight loss, maintenance and gain.
- 1.Y. S. Balance. In: Encyclopedia of Human Nutrition. Vol 2. 2nd ed. Elsevier Academic Press; 2005:2167.