As the battle to reduce the waistlines of Americans and Canadians intensifies, the traditional measure of obesity – the body mass index or BMI – is being questioned by a variety of experts.
“The BMI is useful in providing general guidance,” says LHSFNA Health Promotion Division Director Mary Jane MacArthur, “but increasingly, the waist-to-hip ratio is being recognized as a better personal health risk indicator.”
The BMI compares weight to height, but does not account for the fact that well-trained athletes or weight-lifters may have enough muscle (muscle weighs more than fat) to produce an overweight or obese rating. Similarly, elderly people without much muscle may get an underweight rating when they actually are in good condition. Traditionally, BMIs above 25 are assumed to indicate a higher risk for a number of health disorders, including heart disease.
The WHR ignores overall height and simply divides one’s waist measurement by one’s hip measurement. “The basic idea,” says MacArthur, “is your waist should be significantly smaller than your hips. If it’s not, you need to consider a better diet and more exercise.”
Studies indicate that a WHR greater than 1.0 for men or 0.8 for women is associated with a greater risk of diabetes or hypertension (high blood pressure). Also, WHRs above 0.95 for men and 0.8 for women indicate a heightened risk of heart attack.
In contrast to BMI calculating, measuring WHR is easy. All it requires is a tape to determine the measurements and the division of the waist measurement by the hip measurement. The University of Maryland provides an online WHR calculator for anyone who wants to avoid the long division.
To help with BMI calculations, the Centers for Disease Control recently created a handy, easy-to-use online tool that will produce a BMI rating with a few, quick keystrokes.
After height and weight are entered, the calculator produces a BMI and tells whether the viewer is in the underweight, normal or overweight range. If outside the normal range, it provides a link to information that may help a viewer get within healthy norms.
The calculator has two sections, one for metric and one for ordinary American (English) calculations. It also has a calculator for children and teens as well as adults.
A link is provided to a page “About BMI” which explains BMI and why it can be a useful assessment tool. Links also are provided to other nutrition and weight resources on the Internet.
More information about these tools is available at Waist-to-Hip Ratio Measures Health Risks. An online BMI chart can be found at Taking on Your Own Body’s Weight. For those who need an “in-hand” BMI chart for use at home or in a training class, the LHSFNA publishes a card. It can be ordered through the Fund’s online Publications Catalogue.