Study finds fat levels a better indicator of early death than commonly used BMI measure
By Amy Norton
MONDAY, March 7, 2016 (HealthDay News) -- People who have more body fat -- regardless of their size - may have a higher risk of dying early than people whose bodies have less fat, new research suggests.
The investigators said the findings support the idea that BMI is a fairly crude measure that may not reflect a person's body composition, or be a good indicator of health.
Someone with a lot of muscle mass, for example, may have a high BMI and, technically, fall into the "overweight" category, explained researcher Dr. William Leslie.
So the relationship between body size and health "is more nuanced than the number on your bathroom scale," said Leslie, a professor of medicine and radiology at the University of Manitoba, in Winnipeg, Canada.
"It's important to be attuned to what you're made of, rather than just how much you weigh," Leslie said.
The findings, published online March 8 in the Annals of Internal Medicine, may offer one explanation for the so-called "obesity paradox."
That refers to a counterintuitive pattern that's been seen in a number of studies: Overweight and moderately obese people with heart disease or other chronic ills tend to outlive thinner people with those same conditions.
But those studies have often relied on BMI, Leslie explained. And it's possible that higher BMI reflects greater muscle mass and fitness, or less weight loss from a chronic disease -- as opposed to some protective effect of body fat, he added.
For their study, Leslie's team combed through data on more than 54,000 adults, mostly in their 60s, who'd undergone DXA scans to measure their bone density. Those bone scans have the bonus of allowing an estimate of a person's body fat percentage.
It turned out that men and women with the greatest amounts of body fat were more likely to die over the next four to seven years, the study showed.