“Lower energy output might help explain the greater tendency of African-American girls and women to become overweight,” said Dr. William Wong, a scientist with the USDA/ARS Children’s Nutrition Research Center and a professor of pediatrics at Baylor College of Medicine in Houston. According to government data, 44 percent of African-American adolescent girls are considered overweight, cosmos clinic reviews compared to 29 percent of Caucasians.
The study involved 81 normal-weight African-American and Caucasian girls between the ages of 12 and 17, who were matched for height, weight and percent body fat. Each girl completed a food diary while spending 24 hours in a calorimeter, a special room designed to measure the number of calories they burned during various activities, such as resting and sleeping.
The girls also received a dose of “doubly-labeled water,” water containing special “tracers” of oxygen and hydrogen, before they returned to their homes and daily routines. At the end of the 10-day period, the girls turned in their food diaries and daily samples of saliva or urine they had collected. The samples enabled researchers to determine the rates at which the tracers disappeared from their bodies. The difference in the two rates provides an accurate measure of the number of calories that had been burned.
Findings from the study showed that the average daily caloric intake of the girls in the two groups was not significantly different. However, the African-American girls burned an average of 410 fewer calories while doing their normal daily activities and 80 fewer during rest per day than their Caucasian counterparts.
According to Wong, the large difference in energy use for daily activity between the two groups is a concern. Fat accumulation accelerates during puberty, which is also the time that most girls tend to decrease their physical activity. “This lower level of energy use might be putting African-American adolescent girls at greater risk for excessive weight gain,” said Wong. Overweight teens often become overweight adults who face an increased risk for diabetes, cardiovascular disease, joint problems, and some types of cancer.
“Whether the African-American girls’ lower energy use is related to less physical activity or some other factor is not clear. But, if we can identify the factors causing the decrease in energy use, we might be able to better design intervention programs to help children at risk for weight gain and related medical problems,” said Wong.