RMR (Resting Metabolic Rate)

Resting Metabolic Rate (RMR)Resting Metabolic Rate (RMR) and BMR (Basal Metabolic Rate) are scales of measurements for the metabolism of your body. They indicate the required calorie intake when the body is at complete rest.

The Calculation

There are two popular formulas which can be used to calculate these metabolic rates. Both formulas take into account height, weight, age and gender:

BMR :: Harris-Benedict Equation (from J. A. Harris and F. G. Benedict, 1918)

This formula, generally accepted in the Medicine of Nutrition, is still used today, and offers a good approximation of your energy requirements whilst resting:

For Men:
Basal Energy Expenditure [kcal/24 H.] = 66,47 + (13,7 × Weight [kg]) + (5 × Height [cm]) − (6,8 × Age)

For Women:
Basal Energy Expenditure [kcal/24 H.] = 655,1 + (9,6 × Weight [kg]) + (1,8 × Height [cm]) − (4,7 × Age)

The Mifflin Equation for RMR:

For Men:
Resting Energy Expenditure (kcal/ 24 H.) = (10 x Weight [kg]) + (6.25 x Height [cm]) - (5 x Age) + 5

For Women:
Resting Energy Expenditure (kcal/ 24 H.) = (10 x Weight [kg]) + (6.25 x Height [cm]) - (5 x Age) - 161

Daily Minimum Calorie Requirements:

Depending on activity levels, it is possible to extend the above equations to include average activity levels and thereby to calculate a good guideline for minimum daily calorie requirement which at the same time takes into account age, gender, weight and height.

These equations. however, do not take into account Body Composition (i.e. Body Fat, Muscle Mass and Frame Size, etc.).

The various activity levels are given the following values within the calculation:

Activity Levels Category Description
1.2 Sedentary Little or no exercise and a desk job
1.375 Lightly Active Light exercise or sports 1-3 days a week
1.55 Moderately Active Moderate exercise or sports 3-5 days a week
1.725 Very Active Hard exercise or sports 6-7 days a week
1.9 Extremely Active Hard daily exercise or sports and physical job

Do My Daily Required Calories Change?

As you become older, your RMR will go lower
When you loose weight and become lighter, your RMR will go lower
If you get smaller in height, as is often the case during the aging process, your RMR will go lower

Altogether, when you become older, lighter and/or shorter, you RMR will become lower as before, to keep your weight stable would mean eating less and/or exercising more.

Is the Equation suitable for Sporty People?

Neither of the equations take Body Composition into account and are therefore less accurate for people with an over average amount of muscle mass. The reason being, that muscle burns calories and fat doesn't.

An over average muscular person can expect, from these equations, to have a higher RMR as the calculated result, and similarly, a person with a less than average amount of muscle can expect to have a lower RMR as the calculated result.