CDC Study: BMI Is Incorrect Indicator For 18% Of The U.S.

A recent New York Times article provides specific numbers about the accuracy of a controversial metric often used to determine the health of an individual – body mass index (BMI). BMI is a value derived from the mass (weight) and height of an individual, and in many wellness programs, it is captured through a biometric screening and seen as a key indicator of an employee’s health. Since this number is influential in corporate wellness, the value of BMI as an indicator of health should be very important to employers looking to implement biometric screenings.

The research from the Centers for Disease Control and Prevention and the National Health and Nutrition Examination Survey indicates that BMI is a misleading measure for 18% of the country. To capture this data, researchers recorded the BMI and body fat percentages of more than 5,000 people. As you can see in the graphic below, there is a strong relationship between BMI and body fat percentage, but for almost one in five adults, the two measurements told a different story. The data shows that 12% of males and 3% of females identified as overweight according to BMI had normal body fat percentages. These individuals have been labeled as “healthy obese” because BMI incorrectly labels them as overweight. The data also shows that 6% of males and 15% of females identified as normal or underweight according to BMI had high body fat percentages. These individuals have been labeled as “skinny fat” because BMI incorrectly labels them as being normal or underweight.

BMI is typically used instead of body fat because it is easier and cheaper to acquire the data. Low cost methods for body fat percentages are often inaccurate, which would result in the same dilemma BMI creates for employers. Since most employers extrapolate the BMI information from a subset of employees (because not everyone will participate in a biometric screening) to gauge the health of their entire population, the added complexity of having 18% of the data being an inappropriate indicator of health has to be the proverbial straw the breaks the camels on biometric screenings in the workplace. This is just another reason why we strongly encourage employers to skip the biometric screening. The risks and costs of biometric screenings are far too great. Despite the overwhelming evidence, many employers continue to use this procedure as a large or only part of their wellness program.