How Accurate Is BMI as a Health Indicator?
By Paul Rothbart
Healthcare professionals use various markers to determine the level of health of their patients. Weight, blood pressure, oxygen levels, and cholesterol are some of the most common. Another marker that you've surely heard of is body mass index (BMI). The use of BMI has been hotly debated as to its accuracy in determining a patient's general health. Here is some information everyone should know about BMI.
BMI is a scale that places people into health categories based on the ratio of their weight to their height. Developed in 1832 by Lambert Adolphe Jacques Quetelet, a Belgian mathematician, the basic formula is the person's weight in kilograms divided by their height in meters squared. This number is then applied to a scale to determine the patient's category. A BMI in the range of 18.5 to 24.9 is considered a normal, healthy number. Below that range is underweight and between 25 and 29.9 is overweight. At 30 and above, an individual is considered obese.
Is BMI Accurate?
BMI is not a thorough predictor of health as it leaves out many important factors. It can, however, be a somewhat reliable indicator that a patient may be prone to health problems. There is a considerable body of research to show that people whose BMIs fall outside the normal range tend to be more at risk for some disease and death. A 2017 study of 103,218 people who died that had a 30-year follow-up found that people with a BMI higher than 30 had a 1.5-2.7 times greater risk of death. Other research has found that those in the obese category are at a greater risk of heart and kidney disease, type 2 diabetes, liver disease, and breathing and mobility problems.
Where BMI Is Lacking
Although BMI has accurately predicted a greater risk of many chronic diseases, there are a number of factors it doesn't take into account. It completely ignores a patient's gender, age, lifestyle, and personal and family medical history. It also doesn't take into account how a person's weight is comprised. For example, a bodybuilder may have a BMI in the obese category, but their weight is made up mostly of muscle with a low body fat percentage. This person is most likely in well above average health. Using BMI as a sole indicator of health is a mistake. Many other markers such as blood pressure, cholesterol, and various tests of organ function are necessary for a complete picture.
BMI can be useful as a starting point to determine a patient's general level of health. For full accuracy, other factors must be examined in detail to truly understand how healthy any patient is and how much at risk for disease they may be.
To learn more about your health, wellness and fitness, see your local chiropractor at The Joint Chiropractic in McKinney, Tex.