Someone mentioned this on the radio the other day as well....the waist thing.... "Height and circumference methods There also exist formulas for estimating body fat percentage from an individual's weight and girth measurements. For example, the U.S. Navy Circumference method compares abdomen or waist and hips measurements to neck measurement and height,[10] and other sites claim to estimate one's body fat percentage by a conversion from the body mass index. In the Navy the method is known as the "rope and choke." It is not uncommon for Chiefs to take advantage of flaws in the procedure to pass those who are otherwise out of standards[citation needed]. The U.S. Marine Corps and U.S. Army also rely on the Height and Circumference method. For males, they measure the neck and waist just above the navel. Females are measured around the hips, waist, and neck. These measurements are compared to a height/weight chart with age factored in as well. This method is used because it is a cheap and convenient way to implement a body fat test throughout the entire Department of Defense. This method poses a particular threat of inaccuracy because one can hold one's stomach in more if needed to pass the requirements, and/or flare the neck out and make it bigger resulting in a lower body fat percentage. Due to different body compositions, those with larger necks have an advantage over those with smaller necks. Another well-known method using height and circumference is the YMCA formula. It uses only body weight in pounds, and waist in inches (at navel), to calculate body fat percentage using the formulas, http://upload.wikimedia.org/math/d/d/b/ddbe567bd1a9e582e992c98a3222d1b5.png for women, and http://upload.wikimedia.org/math/5/2/0/520903b16074b2ef4a9e967d1bbe2828.png for men."
