4.2: Part B. Calculating RMR based off of Lean Body Mass (LBM)

Part B. Calculating RMR based off of Lean Body Mass (LBM)

Since lean body tissue is more active than fat tissue, simply using body weight is not an accurate means of estimating metabolic rate for a more muscular person. This is similar to body mass index not being a good gauge of body composition in a heavily muscular person. Use the U.S. Navy formula to estimate LBM.

To use the Katch McArdle or Cunningham formulas you must know someone’s lean body mass. To calculate lean body mass (LBM) you must know your body fat %. In another section we used the U.S. Navy formula to estimate % body fat. If you know your body fat % then à total weight – (total wt X body fat %)= LBM. In example, if you are 80 kilograms and 20% body fat it would be 80 – (80 X .2)= 64 kg of lean body mass. An easy way is also to use (1- (%BF) or .2)* body weight.

1. Katch-McArdle lean body mass RMR calculation,

BMR= 370 + (21.6 x LBM kg) or 370 + (9.82 x LBM in lbs)

2. Cunningham formula also LBM- generally a higher estimation but more accurate for muscular athletes 500 + (22 x kg of LBM)