How accurate is body mass index?

Body mass index (BMI) is a measure of body fat based on height and weight. It is calculated by dividing a person's weight in kilograms by the square of their height in meters. BMI is a simple and inexpensive way to screen for obesity, but it is not always an accurate measure of body fat.

BMI can overestimate body fat in people who are very muscular, such as athletes. This is because muscle weighs more than fat. BMI can also underestimate body fat in people who are very short or very tall.

In addition, BMI does not take into account the distribution of body fat. People who carry their weight around their waist are at higher risk for health problems than people who carry their weight around their hips and thighs.

Despite its limitations, BMI is a useful tool for screening for obesity. It is a good idea to talk to your doctor about your BMI and whether or not it is a good measure of your body fat.

Here are some of the factors that can affect the accuracy of BMI:

* Age: BMI tends to be less accurate in older adults, as they tend to lose muscle mass and gain fat.

* Sex: BMI tends to be less accurate in women than in men, as women tend to have more body fat than men.

* Race: BMI tends to be less accurate in certain ethnic groups, such as African Americans and Asians.

* Body composition: BMI does not take into account the distribution of body fat, which can affect the accuracy of the measurement.

If you are concerned about your weight, talk to your doctor. They can help you determine if BMI is a good measure of your body fat and recommend ways to lose weight if necessary.