Why BMI is Used to Measure Obesity

Why BMI is Used to Measure Obesity

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If you’ve been researching the requirements for bariatric surgery, you’ve probably come across the concept of body mass index, or BMI. In order to qualify, patients need to have a BMI equal to or greater than 40 for bariatric procedures such as the gastric sleeve. However, the Lap-Band® procedure has been approved for patients with a lower BMI.

Most people know that a higher BMI is used as an indicator that an individual is overweight or obese—but what, exactly, is BMI? And what makes it an accurate measurement of obesity when assessing eligibility for bariatric surgery?

What is BMI?

Developed in 1832, BMI, or body mass index, is calculated by dividing a person’s weight (in kilograms) by their height (in meters) squared. This formula results in a number which indicates a person’s excess weight. It’s best used not as a diagnostic tool but as screening tool for various health risks and bariatric surgery eligibility.

It’s also worth mentioning that BMI is not a tool without faults. It’s not an exact measure of a person’s body fat percentage—just a gauge of excess weight. The formula also doesn’t factor in bone mass or muscle, so it tends not to be an accurate measure for those with a lot of muscle, like athletes. BMI also doesn’t take differences in age, sex, and ethnicity into account.

What is a “Normal” BMI?

For adults over 20, the categories for BMI are as follows:

  • Under 18.5—underweight
  • Between 18.5 and 24.9—healthy weight
  • Between 25 and 29.9—overweight
  • Between 30 and 39.9—obese
  • Over 40—morbidly obese

Why is BMI Used to Measure Obesity?

Easily Accessible

BMI is the easiest, most inexpensive indicator of obesity—you just need your height and weight to calculate it. There are other, more accurate methods of measuring body fat, like underwater weighing, isotope dilution, and skin fold measurement, but none of these methods are as easily accessible as BMI measurement. Unlike BMI, these other methods are also difficult to standardize across different practices.

Correlation with Health Risks

It’s important to note that a person’s BMI is not a concrete indicator of their health. However, most studies have found that a higher BMI correlates with current or future health risks, like chronic disease and death, making it an accurate tool for assessing health risks.

BMI Requirements and Lap-Band

In order to meet the requirements for the Lap-Band surgery, patients need to have a BMI of over 40. Alternatively, patients can qualify with a BMI of 35 to 40 if they have a condition that may be relieved with weight loss, like high blood pressure, sleep apnea, or diabetes.

Considering bariatric surgery? To learn more about the qualifications for the Lap-Band procedure and your personal eligibility, talk to one of the experts at the Lap-Band of Louisville. Whenever you’re ready, we’re here to help you make the transition to a healthier lifestyle.