What is BMI, and Why Does It Matter?

Your Body Mass Index, or BMI, is a good indicator of whether you’re at a healthy or unhealthy weight in relation to your height.

Your Body Mass Index, or BMI, is a good indicator of whether you’re at a healthy or unhealthy weight in relation to your height. This numerical value is calculated by dividing your weight in kilograms by your height in meters squared (kg/m2). You can use our BMI calculator, available online at heart.org/bmi, to calculate your BMI. Here’s what the numbers mean:

⇒ A BMI less than 18.5 kg/m2 is considered underweight.

⇒ A BMI between 18.5 kg/m2 and 24.9 kg/m2 is healthy.

⇒ A BMI of 25 kg/m2 to less than 30 kg/m2 is defined as overweight. People with BMIs in this range are usually about 10 percent over their ideal weight and have an increased risk of heart and blood vessel disease.

⇒ A BMI between 30 kg/m2 and 40 kg/m2 indicates obesity, which is about 30 pounds or more overweight. People in this range have a high risk of cardiovascular diseases.

⇒ A BMI over 40 kg/m2 indicates extreme obesity.

The BMI assessment isn’t for everyone and may not be the best method for those who are under age 20, highly trained/athletic, pregnant or breastfeeding. If any of these apply to you, ask your healthcare provider about other ways to assess your body composition.

If you find your BMI is over 25 kg/m2, talk to your healthcare provider about the best ways to drop those extra pounds.

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