Body mass index (BMI), a formula that calculates a person’s body fat using his weight and height, may be responsible for inaccurate health assessments in African-American populations, a new study reveals. “The number used to indicate weight category does not reflect the same amount of body fat for some races compared to others,” according to senior authors of a forthcoming article in British Journal of Nutrition. “The results are consistent with other studies that say BMI is inexact and should be tailored to help target those at risk.” BMI is used to determine weight categories: 18.5 and below is considered underweight; 18.6 to 24.9 healthy; 25 to 29 overweight; and 30-plus obese. “This scale was created years ago and is based on Caucasian men and women,” says Dr. Molly Bray, associate professor of pediatrics and nutrition at Baylor College of Medicine and Texas Children’s Hospital. “It doesn’t take into account differences in body composition between genders, race/ethnicity groups, and across the lifespan.” Rather than basing conclusions on potentially biased methods, the researchers used dual-energy x-ray absorptiometry, a low dose X-ray known as DXA, to determine percent fat.  DXA can be used to estimate bone density, lean mass and fat mass. “When the two results were compared, researchers found that the DXA estimate of percent fat of African-American women was 1.76 percent lower for the same BMI compared to non-Hispanic white women,” Baylor College of Medicine says in a news release. “Since BMI is assumed to represent body fatness, an African-American woman would not be considered overweight or obese until she reached a higher number than what is indicated by the current BMI standards. The opposite is the case for Hispanic, Asian and Asian-Indian woman. Their percent fat is higher by 1.65 percent, 2.65 percent and 5.98 percent, respectively. So they would be considered overweight or obese at amounts lower than what the BMI standards indicates. The results for men were similar.” Says Bray: “Right now non-Hispanic white women are not considered obese until they have a BMI of 30 or above.  Based on our data in young adults, for Hispanic women the number would be around 28. For African-American women, the number to cross is around 32.”

TAGS: African American Health, obesity

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