The obesity crisis in America may be worse than experts thought. A new report suggests the key test used to measure obesity isn't reliable.
Doctors typically use a person's Body Mass Index or BMI to determine whether an individual is overweight.
But new research published this month in the journal PLoS ONE found that the BMI formula often underestimates the level of fat in a person. When comparing the BMI to a blood test and body scan, the BMI results were wrong for half of women and 1 in 4 men.
"Particularly in women, as they age, their muscles become inserted with fat, even though they stay thin and beautiful in a dress," said Dr. Eric Braverman, a New York physician who co-wrote the study.
Experts say alternative tests would reveal that between 50 and 60 percent of Americans can be categorized as obese.
Under the current BMI measurement, the Center for Disease Control says 1 in 3 Americans is obese.
The researchers did say that, although imperfect, the BMI test is important to helping guide doctors on how to treat their patients.
"You have to understand that BMI is an estimate of fatness, it's not a measure of fatness. But there are very few screening-tool estimates we have that are as simple to use," explained Dr. Patricia Choban, medical director of the bariatric-surgery program at Mount Carmel West hospital.
Calculating BMI is also free, compared to scans and tests that often cost hundreds or thousands.
The BMI is determined by multiplying a person's weight by 703, then dividing that number by the person's height in inches.