What is BMI and How is it Calculated?

If you are one of the many people considering weight loss surgery this year, you have likely heard a lot about your BMI (Body Mass Index) and its significance. But what exactly is BMI and how is it calculated? Most importantly, why does it matter?

Body Mass Index (BMI) Calculated

Simply put, BMI is a person’s weight in kilograms divided by the square of height in meters. In American terms, take your weight in pounds and divide it by your height in inches squared. For instance, if you weigh 250 pounds and are 5’4″, you would divide 250 by 64^2. Take that percentage and multiply it by 703 for correct calculation of your individual body mass index. You can also use an online BMI calculator to check your results.

Importance of BMI Results

Why is your BMI so important to your overall health?

BMI does not measure your body fat directly, but it is an excellent indicator for your doctor to determine if you might be at risk for other health problems. Though not a diagnostic tool, BMI is simple and easy to use as a tracking tool for weight gain.

How Doctors Use BMI

BMI is used around the world to place people into weight categories. A BMI score less than 18.5 indicates malnutrition, while 18.5-24.9 show healthy weight. A score higher than 25 might mean you are overweight, and a result greater than 30 shows you are an obesity risk. Because the calculation does not account for gender or muscle mass, it is not flawless. However, as a general rule, when adults gain weight, they are gaining fat and not muscle mass. Some people may fall into an overweight category because of body type. It is always best to discuss the results with your doctor as well as rely on other indicators to determine your health risks. Many patients with BMI above 25 might also be at risk for heart disease, type 2 diabetes, or high blood pressure.

BMI and Gastric Surgery

Most patients seeking gastric surgery have BMI scores greater than 40. While this score varies among patients and other factors are considered, it is a general indicator of obesity. When obese, your body has accumulated enough excess fat to negatively impact your health. Therefore, an awareness of your BMI score can help you determine the steps necessary to improve your overall health. For patients with a BMI less than 40 but who have other chronic health concerns, talk with your doctor about the best plan of action to facilitate your best life.