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Body mass index

Alternative Names

BMI

Information

A good way to assess your weight is to calculate your body mass index (BMI). Your BMI estimates whether you are at a healthy weight. Being overweight puts strain on your heart and can lead to serious health problems. These problems include type 2 diabetes, heart disease, high blood pressure, sleep apnea, varicose veins, and other chronic conditions. More than 300,000 lives could be saved in the United States each year if everyone maintained a healthy weight!

HOW TO DETERMINE YOUR BMI

Your BMI estimates how much you should weigh, based on your height. Here are the steps to calculate it:

• Multiply your weight in pounds by 703.
• Divide that answer by your height in inches.
• Divide that answer by your height in inches again.

For example, a woman who weighs 270 pounds and is 68 inches tall has a BMI of 41.0.

Use the chart below to see what category you fall into, and whether you need to be concerned about your weight.

BMI	CATEGORY
Below 18.5	Underweight
18.5 - 24.9	Healthy
25.0 - 29.9	Overweight
30.0 - 39.9	Obese
Over 40	Morbidly obese

BMI is not always an accurate way to determine whether you need to lose weight. Here are some exceptions:

• Body builders: Because muscle weighs more than fat, people who are unusually muscular may have a high BMI.
• Elderly: In the elderly it is often better to have a BMI between 25 and 27, rather than under 25. If you are older than 65, for example, a slightly higher BMI may help protect you from osteoporosis.
• Children: While an alarming number of children are obese, do not use this BMI calculator for evaluating a child. Talk to your child's doctor about what an appropriate weight is for his or her age.

Doctors use a few different methods to determine whether you are overweight. Your doctor may also take your waist circumference and your waist-to-hip ratio into consideration.

In addition, a lot of other factors influence your health. These include diet, physical activity, smoking, blood pressure, cholesterol levels, and blood sugar levels.

While the exact degree to which increasing BMI levels have a bad effect on human health is unclear, most experts conclude that a BMI greater than 30 (obesity) is unhealthy. Exercise, whatever your BMI, can help reduce your risk of cardiovascular disease and diabetes. Remember to always ask your doctor before starting an exercise program.

Review Date:7/21/2006
Reviewed By:Benjamin W. Van Voorhees, MD, MPH, Assistant Professor of Medicine and Pediatrics, The University of Chicago, Chicago, IL. Review provided by VeriMed Healthcare Network.

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