Friday, May 18, 2012

Body Mass Index (BMI) is a slightly more accurate way of measuring yourself than simply looking yourself up on a healthy weight chart. In combination with your waist measurement (which I cover in “Determining your waist-to-hip ratio” later in this chapter), BMI can tell you if your weight is putting you at risk of developing chronic medical conditions.

You can use either the formula or the chart in the following sections to determine your BMI. The formula is just slightly more precise than the chart; I provide the formula for those of you who like doing diet math. The chart is an easy way out for the rest of you!

Using the formula
To compute your BMI mathematically, use the following formula:
(Your weight in pounds) × 704
divided by (your height in inches)
divided again by (your height in inches)

If your weight is within a healthy range, your BMI will be between 19 and 24. A BMI between 25 and 30 is considered overweight, and a BMI greater than 30 means you’re obese and may be at risk of developing weight-related health problems. If your excess body weight is from muscle, however, a high BMI may not be indicative of health problems.

For instance, if you weigh 153 pounds and you’re 63 inches tall:

153 × 704 = 107,712
107,712 divided by 63 = 1,709.7
1,709.7 divided by 63 = 27.1

In this case, your BMI is 27.1, and you’re considered overweight.

Checking out the chart
To use the chart in Figure 2-2, find your height in the first column, and then move your finger along that row until you find your weight. Move your finger straight up that row until you hit your BMI. Figure 2-2: The Body Mass Index chart shows you if your weight is normal, overweight, or obese.

Use our BODY MASS INDEX CALCULATOR 