Law 1: Determine your body fat percentage so that we can determine your fat free body mass:

A: Determine Your Body Fat Percentage

We need to determine your body fat percentage so that we can determine your fat free body mass.

The "U.S Army method" (AR 600-9) formulas below are a fairly accurate method to determine body fat percentage. However, it isn't as accurate as hydrostatic testing (water dunk tank), which is the gold standard, or a similar high accuracy method that measures displacement in air rather than water (for example, the "Bod Pod"). It also isn't as accurate as skin fold caliper testing if this testing is done by a professional. So, if you have hydrostatic or a skin fold test result, you should use that amount as your body fat percentage. 

The "U.S. Army method" body fat percentage formula for men is:

Men: % body fat = [86.010 x Log (waist – neck)] – [70.041 x Log (height)] + 36.76

The "U.S. Army method" body fat percentage formula for women is:

Women: % body fat = [163.205 x Log (waist + hip – neck)] – [97.684 x Log (height)] – 78.387

 If you don't want to do mathematics, you can temporarily (until we get one going) use this online calculator (http://lowcarbdiets.about.com/library/blbodyfatcalculator.htm) to quickly enter in the numbers. 

If you want to do the calculations, you need a "scientific" calculator. Open the "calculator" on your computer and click on "View" and then choose "scientific". You'll see "log" among the functions of the calculator. Do NOT use the "natural logrithim" (LN) key. For men, take the waist measurement at belly button level. For women, take it at the point of least abdominal width. For the neck, take the measurement as low as possible without including any of the trapezius muscles. Round UP to the nearest .50 when measuring the neck for both genders. Round DOWN to the nearest .50 when measuring the abdomen for both genders. Round UP to the nearest .50 when measuring the hips for females. 

EXAMPLE (MEN): (Neck = 18 in; Waist = 39 in; Height = 72 in)

The equation for men is: % body Fat = [86.010 x Log (waist – neck)] – [70.041 x Log (height)] + 36.76

= [86.010 x Log (39 – 18)] – [70.041 x Log (72)] + 36.76

= [86.010 x Log (39 – 18)] – [70.041 x Log (72)] + 36.76

A. Enter 18.5 and press the LOG key. You should get 1.267 
B. Enter 72 and press the LOG key. You should get 1.857

= [86.010 x 1.322] – [70.041 x 1.857] + 36.76

=[113.72] – [130.066] + 36.76 = 15.66 % body fat percentage
 

Determining Fat Free Body Mass