BMI might seem like just another number attached to your health. Your BMI, or body mass index, is found by dividing your weight in kilograms by your height in meters. It gives you more information than your weight alone, because it puts your weight in context of how tall you are. In other words, BMI accounts for the difference of a 5’2” person weighing 150 pounds and a 5’8” person weighing 150 pounds.
The purpose of measuring BMI, according to the CDC, is to screen for weight category. This is different from determining the level of fat on your body; it also stops short from being an individualized report of your health.
The CDC says the following of BMI’s usefulness and limitations:
“A high BMI can be an indicator of high body fatness. BMI can be used as a screening tool but is not diagnostic of the body fatness or health of an individual.
To determine if a high BMI is a health risk, a healthcare provider would need to perform further assessments. These assessments might include skinfold thickness measurements, evaluations of diet, physical activity, family history, and other appropriate health screenings.”
It’s important to know that a BMI can suggest a weight category (such as underweight, healthy, overweight, etc.), but this suggestion is fallible. A BMI is in no way the end-all, be-all of your health. It can be used to decide if you want other tests to gain a better idea of your personal health—something you may want to do if your BMI is overweight or obese—but the BMI is not holistic in nature. For instance, BMI does not take into account the difference between weight from fat and weight from muscle. An athlete could very easily be considered “obese” when in reality they are very healthy.
For more information about BMI, watch this video from Vox.