Waist to Hip Ratio
The waist to hip ratio compares the measurement of the narrowest part of the waist to the broadest section of the hips. Measure your waist between the rib cage and the hip bone as viewed from the front. The broadest hip/butt measure is best estimated from the side. Do not pull in your stomach while taking your measurements.
Divide the waist measurement by the hip measurement. The ratio should not be more than 0.9 for men and 0.8 for women. For example, a man with a 44-inch waist and 42-inch hips would have a waist/hip ratio of 1.05. As a health indicator, some health practitioners consider this ratio superior to outright waist measurement, especially for heart disease risk assessment. One study found an increased risk of heart disease when this ratio exceeded 0.8 for women and 0.9 for men.
Body Weight and Height Charts
Charts that plot height and weight are used to indicate body mass index. They may also represent healthy weight ranges for men and women. You can see these hanging in many doctors’ and dietitians' offices. Some may be enhanced by including extra information on body frame, age, and more.
Charts are useful tools for getting a snapshot. But to get a more accurate evaluation of health risk in relation to body fatness, other factors need to be considered, too.
Body Calipers
Body calipers are used to measure skinfold thickness at various sites to estimate body fat percentages. Because the degree of error is potentially high, this method of fat measurement is just about useless if not in the hands of an expert-–and that means someone with a lot of practice and validation in order to judge the correct places on the body and the right amount of skinfold to capture. A quality pair of medical calipers is a good start. An affordable personal model with a good reputation is the Accu-Measure 3000.
Bioelectrical Impedance Analysis (BIA)
BIA uses a small electronic pulse that passes through muscle and fat at different rates. However, its measurements may be thrown off by how hydrated you are and how much you've eaten; it may be too inaccurate for anything other than comparative use. Users are encouraged to establish a baseline measurement and repeat measurements under consistent conditions over time to detect changes. Tanita is a popular brand.
DEXA Scanning
DEXA stands for dual energy x-ray absorptiometry and is sometimes simply called DXA. DEXA is most often used to measure bone density and lean mass, but it can also deliver fat mass readings. The system uses a body scanner, and the process can take about 15 minutes and cost upward of $100 depending on where you live and the availability and use of such technology. It appears to be quite accurate within about a 3 percent error.
Water Weighing
Essentially this entails dunking you completely underwater while you sit on scales and expel all air from the lungs. The technology is based on the displacement of water and the different density of fat and lean muscle mass. This is also an accurate method, although mainly restricted to academic and research establishments because of the enveloping nature of the procedure.
The Bod Pod
This device has been around for about 10 years and may be the best of all. The Bod Pod is an egg-shaped cocoon within which you are enclosed for about 5 minutes. It works on the same principle as water weighing except you displace air instead of water. It's called "plethysmography". No mess, no fears of drowning. It is reported to have an accuracy of 2 percent.
Summary
You don’t necessarily need a measure of body fat to know you’re making progress on a diet and exercise program. For bodybuilders and sportspeople with critical standards for body fat, measurement may be more crucial. Sometimes though, it helps to know that you are losing fat and holding on to, or even gaining, muscle. Ordinary bathroom scales do not necessarily reflect this.
Sources Brunet M 2nd. Female athlete triad. Clin Sports Med. 2005 Jul;24(3):623-36, ix. Review. International Diabetes Federation. The IDF Consensus Worldwide Definition of the Metabolic Syndrome. www.idf.org/ Welborn TA, Dhaliwal SS. Preferred clinical measures of central obesity for predicting mortality. Eur J Clin Nutr. 2007 Feb 14. Alvarez VP, Dixon JB, Strauss BJ, et al. Single frequency bioelectrical impedance is a poor method for determining fat mass in moderately obese women. Obes Surg. 2007 Feb;17(2):211-21. Vescovi JD, Zimmerman SL, Miller WC, et al. Evaluation of the BOD POD for estimating percentage body fat in a heterogeneous group of adult humans. Eur J Appl Physiol. 2001 Aug;85(3-4):326-32.
Fox CS, Massaro JM, Hoffmann U, et al. Abdominal Visceral and Subcutaneous Adipose Tissue Compartments. Association With Metabolic Risk Factors in the Framingham Heart Study. Circulation. 2007 Jun 18.
