Body Mass Index

Body mass index, or BMI, is a measurement that compares your weight to your height. It is useful because it is very easy and quick to calculate. To determine your BMI, use one of the following equations.

1. If you know your weight in kilograms (kg) and your height in metres (m), then BMI = (weight)/(height x height).

2. If you know your weight in pounds (lb) and your height in inches (in), then BMI = (weight x 703)/(height x height).

Once you have calculated your BMI, use the following ranges to determine whether your weight is appropriate for your height:

BMI less than 16.5 = Severely underweight
BMI from 16.5 to 18.5 = Underweight
BMI from 18.5 to 25 = Normal
BMI from 25 to 30 = Mildly obese
BMI from 30 to 35 = Moderately obese
BMI greater than 35 = Severely obese

While scientific studies have shown that people who have a BMI greater than 25 are at increased risk for obesity-related health problems, keep in mind that the BMI calculation does not take into consideration your proportion of body fat to lean body mass. Thus, if your BMI is greater than 25 but you have a low amount of body fat relative to lean body mass, then your risk of developing obesity-related health problems is probably not as high as predicted. Also, someone who falls into the normal range for BMI, yet who has a very high amount of body fat relative to lean body mass could have a higher risk of developing obesity-related health problems.