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Body mass index

BMI; Obesity - body mass index; Obesity - BMI; Overweight - body mass index; Overweight - BMI

A good way to decide if your weight is healthy for your height is to figure out your body mass index (BMI). You and your health care provider can use your BMI to estimate how much body fat you have.

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Being obese puts strain on your heart and can lead to serious health problems. These include:

HOW TO DETERMINE YOUR BMI

Your BMI estimates how much you should weigh based on your height.

There are many websites with calculators that give your BMI when you enter your weight and height.

You can also calculate it yourself:

For example, a woman who weighs 270 pounds (122 kilograms) and is 68 inches (172 centimeters) tall has a BMI of 41.0.

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

Use the chart to see what category your BMI falls into
BMICATEGORY
Below 18.5Underweight
18.5 to 24.9Healthy
25.0 to 29.9Overweight
30.0 to 39.9Obese
Over 40Extreme or high risk obesity

BMI is not always the best way to decide whether you need to lose weight. If you have more or less muscle than is normal, your BMI may not be a perfect measure of how much body fat you have:

Providers use a few methods to decide whether you are overweight. Your provider may also take your waist circumference and waist-to-hip ratio into consideration.

Your BMI alone can't predict your health risk, but most experts say that a BMI greater than 30 (obesity) is unhealthy. No matter what your BMI is, exercise can help reduce your risk of developing heart disease and diabetes. Remember to always talk to your provider before starting an exercise program.

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References

Centers for Disease Control and Prevention website. About adult BMI. www.cdc.gov/healthyweight/assessing/bmi/adult_bmi/index.html. Updated September 17 2020. Accessed December 3, 2020.

Gahagan S. Overweight and obesity. In: Kliegman RM, St Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 60.

Jensen MD. Obesity. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 207.

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Review Date: 8/13/2020  

Reviewed By: Linda J. Vorvick, MD, Clinical Associate Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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