Harvard Heart Letter

Weighing in on the value of the body mass index

Your BMI estimates your body fat better than the number on a scale. But a tape measure is an equally important tool.


As your BMI rises above 25, so does your risk for developing high blood pressure, diabetes, and cardiovascular disease.
Image: designer491/iStock

The body mass index (BMI), a measurement derived from the relationship between your weight and your height (see box), is a common way to estimate body fat. It's a simple, fast, and essentially free tool that enables doctors to help identify people who might be at risk for health problems—including cardiovascular disease—that are linked to excess body fat.

People with a healthy BMI (18.5 to 24.9) tend to have better blood sugar and blood lipid levels compared with people whose BMI values fall above that range. They're also more likely to have normal blood pressure, which puts less strain on the heart and circulatory system. They're less prone to joint and muscle aches and may even have more energy—factors that make heart-healthy exercise less of a chore.

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