Body mass index, or BMI, is a measure of body size. It combines a person's weight with their height. The results of a BMI measurement can give an idea about whether a person has the correct weight for their height.  BMI is a screening tool that can indicate whether a person is underweight or if they have a healthy weight, excess weight, or obesity. If a person's BMI is outside of the healthy range, their health risks may increase significantly.

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Carrying too much weight can lead to a variety of health conditions, such as type 2 diabetes, high blood pressure, and cardiovascular problems. A weight that is too low can increase the risk of malnutrition, osteoporosis, and anemia.

 

BMI does not measure body fat directly, and it does not account for age, sex, ethnicity, or muscle mass in adults. However, it uses standard weight status categories that can help doctors to track weight status across populations and identify potential issues in individuals.