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How to Measure Your Body Mass Index (BMI) and Waist Circumference

Overweight, Obesity and Body Fat Distribution Measures

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Updated January 29, 2014

Health care providers use body mass index (BMI) and waist circumference measures to assess a person's risk of developing diabetes, arthritis, and other health conditions. About 64.5% of U.S adults are overweight or obese. How do you know if you are among them? Two easy measures, body mass index (BMI) and waist circumference, provide useful estimates of overweight, obesity, and body fat distribution. Learn how to measure your BMI and waist circumference, and what these measures mean for your health.

Difficulty: Easy

Time Required: 10 Minutes

Here's How:

  1. BMI measures your weight in relation to your height, and is closely associated with measures of body fat. You can calculate your BMI using this formula: BMI equals a person's weight in pounds divided by their height in inches squared, multiplied by 703. For example, for someone who is 5 feet, 7 inches tall (67") and weighs 220 pounds, the calculation would look like this: 220 divided by 4489 (67" X 67") multiplied by 703 = 34.45 BMI

  2. You can also estimate your BMI with this chart: Body Mass Index (BMI) Chart
    • A person with a BMI of 18.5 to 24.9 is considered healthy.
    • A person with a BMI of 25 to 29.9 is considered overweight.
    • A person with a BMI of 30 or more is considered obese.
  3. 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 unhealthy range, but still be healthy and have little risk of developing diabetes or having a heart attack.
  4. 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/Latino American women. But for most people, BMI is a reliable way to tell if your weight is putting your health at risk.
  5. Excess weight, as measured by BMI, is not the only risk to your health -- so is the location of fat on your body. If you carry fat mainly around your waist, you are more likely to develop health problems than if you carry fat mainly in your hips and thighs. This is true even if your BMI falls within the normal range.

  6. To measure your waist circumference, place a tape measure around your bare abdomen just above your hip bone. Be sure that the tape is snug, but does not compress your skin, and is parallel to the floor. Relax, exhale, and measure your waist. Women with a waist measurement of more than 35 inches or men with a waist measurement of more than 40 inches may have a higher disease risk than people with smaller waist measurements because of where their fat lies.
  7. Extra weight can put you at higher risk for these health problems:

    • type 2 diabetes (high blood sugar)
    • high blood pressure
    • heart disease and stroke
    • some types of cancer
    • sleep apnea (when breathing stops for short periods during sleep)
    • osteoarthritis (wearing away of the joints)
    • gallbladder disease
    • liver disease
    • irregular menstrual periods

    If your BMI is between 25 and 30 and you are otherwise healthy, try to avoid gaining more weight, and look into healthy ways to lose weight and increase physical activity.

  8. Talk to your health care provider about losing weight if your BMI is 30 or above, or your BMI is between 25 and 30 and you have:
    • two or more of the health problems listed above or
    • a family history of heart disease or diabetes, or
    • your waist measures over 35 inches (women) or 40 inches (men)-even if your BMI is less than 25-and you have:
    • two or more of the health problems listed above or
    • a family history of heart disease or diabetes.

    Source: NIH Publication No. 04-5283, Weight and Waist Measurement: Tools for Adults

Related Video
How to Calculate BMI

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