Comparison of risk factors for obesity in young, nonobese African-American and Caucasian women.
OBJECTIVE
To determine whether specific risk factors for obesity were more evident in young, normal-weight African-American (AA) compared to Caucasian-American (CA) women.


METHODS
Cross-sectional age-matched study.


METHODS
Young, nonobese, sedentary AA (n= 13, 22.5y of age, 23.6% body fat) and CA women (n = 11, 21.5y of age, 24.0% body fat).


METHODS
Aerobic physical fitness (peak VO2), resting metabolic rate (RMR), resting and submaximal exercise fat oxidation rates, total daily energy expenditure (TDEE) by the doubly-labeled water method, physical activity energy expenditure (PAEE), skeletal muscle glycolytic (phosphofructokinase activity (PFK)) and beta-oxidative (beta-hydroxy-acyl CoA dehydrogenase (beta-HADH)) activity, and insulin sensitivity estimated by the insulin-augmented frequently sampled intravenous glucose tolerance test.


RESULTS
The AA and CA subjects were similar in age, body mass index and body composition, but the AA women exhibited lower peak VO2. There were no group differences in RMR adjusted for body composition, or in the rates of submaximal exercise energy expenditure or fat oxidation, and no difference in skeletal muscle beta-HADH or PFK activity. The AA women exhibited lower insulin sensitivity and greater acute insulin response to glucose. The mean TDEE for the AA women was only 74% that of the CA women, primarily due to a lower physical activity energy expenditure (AA group: xPAEE = 1,246+/-438 kJ/day; CA group: x= 3,310+/-466 kJ/day.


CONCLUSIONS
These data indicate that PAEE and its correlates of peak aerobic capacity and insulin sensitivity are lower in young, nonobese AA women compared to their CA counterparts.
Melby
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Department of Food Science and Human Nutrition, Colorado State University, Fort Collins 80523, USA. Melby@cahs.colostate.edu
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D000293:Adolescent; D000328:Adult; D044383:Black People; D003430:Cross-Sectional Studies; D004734:Energy Metabolism / Q000235:genetics / Q000502:physiology*; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood; D018482:Muscle, Skeletal / Q000378:metabolism*; D009765:Obesity / Q000208:ethnology / Q000235:genetics / Q000517:prevention & control*; D010101:Oxygen Consumption / Q000235:genetics / Q000502:physiology*; D012307:Risk Factors; D044465:White People; D001741:Black or African American
D007328:Insulin