This article is from the Diet FAQ, by Claudia McCreary firstname.lastname@example.org with numerous contributions by others.
If you're overweight you probably already know it, but there are a couple of
indicators that can let you know whether your weight increases your risk for
health problems like heart disease. Waist-to-hip ratio is a useful
indicator, and is simple to determine. Stand in front of a full-length
mirror so that you can easily see the areas you are measuring. Use a tape
measure to measure your waist circumference at the level of your navel.
Next, measure your hip circumference at its widest point. (Do not pull the
tape measure too tightly.) Divide your waist measurement by your hip
measurement to determine your waist-to-hip ratio. For example, if your waist
measures 26" (66 cm.) and your hip measurement is 36" (91.5 cm.), your
waist-to-hip ratio is 0.7. For men, a waist-to-hip ratio of 0.95-1.0 or
greater indicates an increased risk for heart disease. Women should have a
ratio of 0.8 or less.
Another useful measurement is your Body Mass Index (BMI). If you have a Web
browser (such as Netscape) which is capable of displaying tables, check out
http://www.loop.com/~bkrentzman/obesity/bmi1.html for a handy BMI chart. To
determine your BMI manually, multiply your weight in pounds by 703, then
divide by the square of your height in inches. For example, if you weigh 130
pounds and are 5'4" (64") tall, your BMI is (130 * 703)/(64 * 64) = 22.3.
(If you use the metric system, divide your weight in kilograms by the square
of your height in meters.) A BMI of 25 or less indicates that you are at low
risk for heart disease; 30 or higher suggests that you are at moderate to
very high risk. BMI, like height/weight charts, does not take into account
individual physiques, body fat percentages, etc., but does at least allow
for a range of weights.