BMR stands for Basal Metabolic Rate. It is the number of calories your body needs while at rest. This does not include the calories that are burned during any sort of physical activities. BMR includes calories required to maintain normal body functions such as your heart rate, respiration and body temperature. You must meet your BMR needs before any physical activity can be done. BMR accounts for 60 to 70 % of your calorie requirements and lifestyle makes up the remainder.
This BMR calculation uses the Harris-Benedict formula, which uses variables of height, weight, age, and gender. This is considered more accurate than calculating calorie needs based on total body weight alone. The only factor not included in the calculation is lean body mass, so if you are very lean the results will not be quite as accurate.
