The traditional measure of healthy weight, Body Mass Index (BMI), may be fundamentally flawed, according to groundbreaking research from the University of Florida (UF). The study suggests that BMI is not the most reliable predictor of future health risks associated with weight.
A more accurate method, bioelectrical impedance analysis (BIA), which has been available for decades, has emerged as a superior alternative. This technique directly measures body fat and has shown a stark contrast to BMI in assessing health risks. In a nationally representative analysis, individuals with high body fat levels, as measured by BIA, faced a 262 percent increased risk of death from heart disease compared to those with lower levels.
The Flaws of BMI
BMI, a simple calculation comparing a person’s weight to their height, has long been the standard for assessing obesity, endorsed by major health organizations such as the CDC, NIH, WHO, and AHA. However, recent scrutiny has highlighted its limitations. BMI does not account for variations in body build, age, gender, race, or ethnicity, prompting some medical organizations to advise against its use as a primary health measure.
Dr. Andrew Freeman, a cardiologist not involved in the UF study, expressed concern over the reliance on BMI. “It’s scary to think that we may have been using a surrogate – BMI – that may not have been all that accurate over the years,” he told CNN.
The Rise of Bioelectrical Impedance Analysis
Health services researcher Arch Mainous and his UF colleagues propose BIA as a more accurate alternative. This method involves a portable, inexpensive device that sends a weak electric current through body tissue to determine muscle and fat composition. Although BIA has been commercially available since the 1980s, it is only recently that modern fitness trackers and smartwatches have begun incorporating BIA sensors.
Despite some variability in measurements, UF’s study indicates that BIA is a more reliable health indicator than BMI. Over 15 years, researchers found that adults with high body fat, as measured by BIA, were 78 percent more likely to die of any cause than those with lower body fat levels. In contrast, higher BMI levels did not correlate significantly with all-cause mortality.
Implications for Future Health Assessments
The findings of the UF study could potentially revolutionize how health risks are assessed. Lead author Mainous describes the study as a “game-changer,” likening it to a “Coke versus Pepsi test” where BMI failed. The simplicity of BMI is overshadowed by its limitations, such as misclassifying muscular individuals as overweight or obese and failing to identify those with normal BMI but high body fat percentages who may be at risk for conditions like metabolic syndrome or type 2 diabetes.
Mainous and his team argue that BIA devices, being both inexpensive and compact, could become a staple in medical clinics. They predict that if further validated in larger and more diverse cohorts, “it is likely that measuring body fat percentage with BIA will become a standard of care.”
“These data will drive better discussions in the doctor’s office as well as public health initiatives with the goal of improving the health of all,” the researchers conclude.
The study, published in the Annals of Family Medicine, marks a significant step towards more accurate health assessments and could lead to changes in public health policies and clinical practices worldwide.
