New Research Questions the Importance of BMI
HealthDay News — Body mass index (BMI) may not accurately reflect a person's body composition, or be a good indicator of health, according to research published online March 8 in the Annals of Internal Medicine.
William Leslie, MD, a professor of medicine and radiology at the University of Manitoba in Winnipeg, Canada, and colleagues evaluated data on 54,420 adults, mostly in their 60s, who'd undergone dual-energy X-ray absorptiometry scans.
The researchers found that men and women with the greatest amounts of body fat were more likely to die over the next four to seven years. Men in the top 20% had at least 36% body fat. And those with highest body fat were up to 59% more likely to die during the study period, versus men whose body fat was in the 28 to 32% range -- which was about average for the group. The difference was smaller among women. Still, those with the highest percentage of body fat – about 39% fat or higher – were 195 more likely to die during the study period, compared with women in the 30 to 34% range (about average for the group).
In contrast, people with a BMI high enough to classify them as obese didn't show an increased death risk. And they were actually less likely to die than men and women with the lowest BMIs -- lower than 24 or 25 kg/m². In these older adults, Leslie told HealthDay, a lower BMI may reflect waning muscle mass or frailty.