Your lean body mass is the weight of all the tissue in your body except fat. You can use formulas available from fitness author and former Mr. America, Mr. World and Mr. Universe Dave Draper to estimate your lean body mass from a few basic body measurements, which will allow you to calculate the percentage of your body weight that comes from fat, also known as your body fat percentage. Body fat percentage is generally a more significant measure of fitness than total body weight, because you may gain muscle weight as your fitness improves.
Step 1
Measure your waist at the naval to obtain its measurement in inches. Weigh yourself on a bathroom scale that uses pounds. Perform these measurements when you first wake up so that your water weight will be at its lowest level of the day.
Step 2
Perform additional measurements if you’re female. Measure your wrist, forearm and hips at their fullest point. Ensure that these measurements are in inches.
Step 3
Compute the lean body mass for males with the following equation from Dave Draper: 1.082 x weight - 4.15 x waist measurement + 94.42.
If your weight is 156 lbs. and your waist measurement is 32 inches in this example, you have a lean body mass of 130 lbs.
Step 4
Calculate the lean body mass for females with this equation from Dave Draper:
0.732 x weight - 0.157
x waist measurement + wrist measurement /
3.14 + forearm measurement x 0.434
- hip measurement x 0.249 + 8.987
Let your weight be 128 lbs., and let your waist measurement be 28 inches in this case. Assume your wrist measures 6.5 inches, your forearm measures 9 inches and your hips measure 38 inches. You have a lean body mass of 95 lbs.
Step 5
Derive your body fat percentage from your lean body mass with this formula from Dave Draper: body weight - lean body mass x 100 / body weight.
If you weigh 156 lbs. and have a lean body mass of 130 lbs., your body fat percentage is 16.7 percent.
Things You'll Need
- Bathroom scale
- Tape measure
- Calculator
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