How to Measure Internal Body Fat

Although your percentage of internal body fat may not directly indicate your level of fitness, it is a valuable piece of information in assessing your susceptibility to certain health problems, such as heart disease, and is also useful in judging the long-term results of exercise. You can find out your body fat percentage by visiting a doctor or fitness trainer, but you can also perform the measurement yourself using some simple tools and formulas.

Things You'll Need

• Tape measure
• Calculator
• Scale

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Instructions

• 1

  Measure the circumference of the largest part of your waist with a tape measure and obtain the value in inches.

• 2

  Step on a scale, weight yourself and obtain your value in pounds.

• 3

  Calculate your lean body mass by using the formula: Lean Body Mass (LBM) = 94.42 + (1.082 x weight) - (4.15 x waist).

  For example, if your waist is 35 inches and your weight is 185 lbs., multiply your weight (185) by 1.082, which equals 200.17. Then multiply your waist measurement (35) by 4.15 to obtain 145.25. Subtract the latter value (145.25) from the former (200.17), which results in 54.92. Add that amount to 94.42 for an LBM of 149.34.

• 4

  Use your LBM to find your body fat percentage using the following formula:

  ((body weight - lean body mass)/ body weight) x 100

  Using our hypothetical measurements, we subtract LBM (149.34) from weight (185) to get 35.66, which we divide by weight (185), for a result of .19. Multiply this number by 100 for the final value of 19 percent.