Basal Metabolic Rate (BMR) Research Models

All web based calorie calculators *estimate* your BMR based upon various research that has been done. These research studies have come up with various formulas that are used to estimate your calories. For example, two of the most commonly used equations come from the research done by Harris-Benedict in 1919 or Mifflin-St Jeor done in 1990. The Mifflin-St Jeor appears to be about 5% more accurate than the Harris-Benedict equations, this is probably because the older research was based upon a population that was much leaner and more active than we currently have. These equations based upon the research are easy to use but only get you to within about +/-10% accuracy on the caloric estimation which is accurate enough for most uses given the difficulty of counting the calories accurately. The reason for the +/-10% variation is twofold. First, because these equations use weight and not lean body mass in their calculations. The energy required to maintain muscle is higher than the energy required to maintain fat so both these equations will be off for either very lean or very fat people. To get around this problem there are two more sets of equations based upon the research by Katch-McArdle and Cunningham which are based upon Lean Body Mass (LBM) instead of weight. Everything has flaws and the Cunningham and Katch-McArdle equations do to. Whose equations should you use for best accuracy?  If you know your body fat accurately, then I suggest using the Katch-McArdle formula, otherwise use Mifflin- St Jeor.  For those who want to know, here are the equations:

Researchers Gender Equation
Harris-Benedict male 66 + 13.7*Weight + 5*Height – 6.8*Age
Harris-Benedict female 655 + 9.6*Weight + 1.8*Height – 4.7*Age
Mifflin-St Jeor male 9.99*Weight + 6.25*Height – 4.92*Age + 5
Mifflin-St Jeor female 9.99*Weight + 6.25*Height – 4.92*Age -161
Katch-McArdle N/A 370 + 21.6*LBM
Cunningham N/A 500 + 22*LBM
Note: All weights in kilograms and heights in centimeters