The body mass index (BMI) scale may be drastically inaccurate, resulting in higher obesity numbers than previously thought. According to a recent study, national statistics showing 30 percent of the population as obese would be doubled to reflect the real number.
BMI is calculated by using a height to weight ratio, but according to Dr. Nirav Shah, the current New York state health commissioner and Dr. Eric Braverman, president of the Path Foundation in New York City, more accurate measurements focus on the percentage of fat combined with the BMI scale.
“If you’re counting on looking at your body fat, based on body mass index, it’s virtually completely unreliable. (With BMI only) roughly 30 percent of Americans are obese, but when you use other methods, closer to 60 percent are obese,” said Braverman. “We are fatter than we realize; it’s the percent of body fat, not BMI, that makes you obese. We call BMI the ‘baloney mass index’.”
A test group of 1,300 people, both men and women, were followed during the study. Each individual was administered a dual-energy X-ray absorptiometry (DEXA) scan, a diagnostic tool measuring bone density, muscle mass, and body fat. The DEXA scan revealed 48 percent of women had been classified incorrectly by the BMI scale as being of normal weight when they were actually obese. Of the men in the study, 25 percent were also classified as obese when they were really not.
Researchers believe the prevalence of obesity in women is due to physical changes while aging. A women’s body tends to replace muscle tissue with fat later in life, complicated by a loss of bone density. The individual’s weight may remain the same, but the distribution of various body tissue is different, resulting in obesity.
Though effective, DEXA scans are too expensive for the average person to undergo. As an alternative, Braverman suggests testing levels of the hormone leptin. “Leptin is a better marker of obesity in women,” he said.
In a healthy woman of normal weight, leptin levels are lower than 5 nanograms per milliliter. Obese women have leptin levels over 10 nanograms per milliliter. Though not as effective of an obesity marker in men, Braverman anticipates an increase in leptin testing in medical practice.
“Everyone is going to get a leptin level just as they do cholesterol [reading] today,” he remarked.