Body mass index (BMI) is a way to determine if someone has excess weight. University of Pennsylvania physicians are asking for a better, more accurate test, but Victoria Brockhouse, assistant medical director at Student Health Services, believes otherwise.
“BMI is used as a screening tool to identify unhealthy weights in adults. It is not a diagnostic tool…To determine health risk, further assessment testing will need to be done by a healthcare provider,” Brockhouse said.
BMI is a simple, inexpensive way to compare large populations across a span of time.
It is calculated by an individual’s weight in kilometers divided by height in meters squared.
If this calculation yields a number 30 or higher it means the individual is considered obese and is at risk for disease, according to BMI standards.
“BMI is a reliable indicator of body fat for most people,” Brockhouse said.
The physicians from the University of Pennsylvania found that 10 percent of the nation’s obese adults are metabolically healthy, showing a flaw in BMI testing.
Brockhouse said a subset of the population is overweight with normal lab tests and normal physicals.
Physicians from the University of Pennsylvania also found weight status and metabolic health are not perfectly correlated, causing them to doubt BMI testing.
Brockhouse, however, believes BMI testing is an accurate first step in the screening process.
“Just as there are 10 percent of obese people that are healthy, there are 8 percent of normal-weight people that are unhealthy,” she explained. “Obviously, you don’t have to be obese to have diabetes, heart disease or cancers.”
She said BMI only tells you, in an indirect way, a person’s body fatness. Other evaluations need to be done to determine fitness.
The inaccuracy the physicians from the University of Pennsylvania found seem to be something Brockhouse is not concerned with.
“Along with BMI testing, there should be additional testing. This might include looking at an individual’s family history, physical activity and, of course, diet choices,” Brockhouse said. “There are other health screenings that could be done to help assess overall risk for obesity-related diseases.”
Brockhouse said because BMI testing only requires height and weight, it is an inexpensive tool for clinicians to use to assess patients.
“BMI is not a problem. It is simply a screening tool used,” she added.