Estimates for Basal Metabolism Inaccurate
for African American Girls
April 16, 1997
The equations used to estimate the
number of calories adolescent females burn while resting are inaccurate for
African Americans, according to a study by the
Agricultural Research Service.
The finding at the agencys Childrens Nutrition Research
Center is important because the basal metabolic rate (BMR) accounts for
between 50 and 70 percent of the calories we burn daily. Clinicians routinely
use BMR to estimate the energy needs of patients. Government agencies use it to
recommend calorie intakes.
Ethnic background should be included in future BMR measurements and in
refining equations used to estimate it, the scientists concluded.
They had suspected that the equations now used do not reflect the energy
needs of children and adolescents, particularly non-white youths, because these
equations were derived from measurements done mostly on white adults.
Whats more, most of the measurements were done during the first half of
the century when equipment and methods were less sophisticated.
Their suspicions were confirmed after careful measurements of 76 white
females and 42 black females between 8 and 17 years old. Nine of the 10
equations they evaluated significantly overestimated BMR in the black girls,
and half overestimated BMR in the white girls.
The ethnic differences became obvious when the two groups were matched for
age, weight and sexual maturity. In six of the 10 equations, the overestimation
was significantly greater for the black girls--averaging 77 calories
daily--than for the white girls, averaging 25 calories daily. The black girls
were heavier, had a higher body mass index than the white girls of the same age
and were more sexually mature, a factor that increases overestimation, the
Scientific contact: William W. Wong,
USDA-ARS Childrens Nutrition Research
Center, Houston, Texas, phone (713) 798-7168,