More on Obesity - BMI

Today, 66 percent of adults in the United States are considered overweight or obese. How do you know if you are among them? Two simple measures, body mass index (BMI) and waist circumference, provide useful estimates of overweight, obesity, and body fat distribution.

Health care providers also use BMI and waist circumference measures to assess a person’s risk of developing diabetes, heart disease, or other health problems. This fact sheet tells you how to measure your BMI and what this measure means for your health.

Today, 66 percent of adults in the United States are considered overweight or obese. How do you know if you are among them? Two simple measures, body mass index (BMI) and waist circumference, provide useful estimates of overweight, obesity, and body fat distribution.

BMI measures your weight in relation to your height, and it is closely associated with measures of body fat. You can calculate your BMI using this formula.

BMI = weight in pounds times 703 divided by (height in inches squared)

For example, for someone who is 5 feet, 7 inches tall and weighs 220 pounds, the calculation would look like this:

BMI equals 220 pounds times 703 inches divided by 67 inches squared equals 154,660 divided by 4489 equals 34.45

A BMI of 18.5 to 24.9 is considered to be in the healthy range. A person with a BMI of 25 to 29.9 is considered overweight, and a person with a BMI of 30 or more is considered obese.

You can also find your weight group on the chart below. The chart applies to all adults. The higher weights in the healthy range apply to people with more muscle and bone, such as men. Even within the healthy range, weight gain could increase your risk for health problems.

Because BMI does not show the difference between fat and muscle, it does not always accurately predict when weight could lead to health problems. For example, someone with a lot of muscle (such as a body builder) may have a BMI in the overweight or obese range, but still be healthy and have little risk of developing diabetes or having a heart attack.

BMI also may not accurately reflect body fatness in people who are very short (under 5 feet) and in older people, who tend to lose muscle mass as they age. And it may not be the best predictor of weight-related health problems among some racial and ethnic groups, such as African-American and Hispanic-American women. But for most people, BMI is a reliable way to tell if your weight is putting your health at risk.

National Institute of Diabetes and Kidney Diseases, 2009