Basal Metabolic Rate (BMR), and the closely related resting metabolic rate (RMR), is the amount of daily energy expended by humans and other animals at rest. Rest is defined as existing in a neutrally temperate environment while in the post-absorptive state.
The body's generation of heat is known as thermogenesis and it can be measured to determine the amount of energy expended. BMR decreases with age generally (as people usually don't maintain lean body mass) and with the loss of lean body mass. Increasing muscle mass increases BMR. Aerobic fitness level, a product of cardiovascular exercise, while previously thought to have effect on BMR, has been shown in the 1990s not to correlate with BMR, when fat-free body mass was adjusted for. New research has however come to light which suggests anaerobic exercise does increase resting energy consumption. Illness, previously consumed food and beverages, environmental temperature, and stress levels can affect one's overall energy expenditure as well as one's BMR.
BMR is measured under very restrictive circumstances when a person is awake. An accurate BMR measurement requires that the person's sympathetic nervous system not be stimulated, a condition which requires complete rest. A more common and closely related measurement, used under less strict conditions, is resting metabolic rate (RMR).
The formula for determining your BMR:
For men:
bmr [kcal/24 h] = 66.47 + 13.7 × weight [kg] + 5 × size [cm] − 6.8 × age [years]
For women:
bmr [kcal/24 h] = 655.1 + 9.6 × weight [kg] + 1.8 × size [cm] − 4.7 × age [years]
Example:
For example, a 38 year old woman weighing 140lbs (63.5kg) and 5 feet 6 inches tall (167.6cm) would calculate as follows:
bmr [kcal/24 h] = 655.1 + (9.6 x 63.5) + (1.8 x 167.6) - (4.7 x 38)
bmr [kcal/24 h] = 655.1 + 609.6 + 301.68 - 178.6 = 1387.78
Use our free BMR calculator to determine your BMR: