Basal Metabolic Rate (BMR)
Basal Metabolic Rate (BMR) is the amount of energy expended while at rest in a neutrally temperate environment, in the post-absorptive state (meaning that the digestive system is inactive, which requires about twelve hours of fasting).
The release of energy in this state is sufficient only for the functioning of the vital organs, such as the heart, lungs, brain and the rest of the nervous system, liver, kidneys, sex organs, muscles and skin. BMR decreases with age and with the loss of lean body mass. Increasing muscle mass increases BMR.
There are different ways to calculate BMR and we use the Katch-McArdle Formula (Resting Daily Energy Expenditure):
P = 370 + (21.6 x LBM)
where LBM is the lean body mass in kg.