Metabolic propensity toward obesity in black vs white females: responses during rest, exercise and recovery.

OBJECTIVE: To examine the existence of a metabolic propensity toward the development of obesity in black vs white females.
DESIGN: Cross-sectional comparison of responses during 30 min of rest, 30 min of treadmill exercise at 65% VO2max, and 30 min of recovery.
SUBJECTS: 22 (11 black, 11 white) healthy, normal weight, sedentary females with a family history of obesity. MEASUREMENTS: Biometric measures (body mass index, waist-to-hip ratio, and body composition by hydrodensiometry) to insure inter-group homogeneity. Oxygen consumption (VO2), respiratory exchange ratio (RER), insulin, glucose and free fatty acids (FFA) during rest, exercise and recovery were measured to test for metabolic differences between the groups.
RESULTS: Black females displayed lower VO2 during rest (p = 0.04) and recovery (p = 0.04), higher RER during rest, exercise and recovery (p = 0.003), and higher levels of insulin (p = 0.03). No significant differences were observed for levels of blood glucose (p = 0.29) or serum FFA (p = 0.73).
CONCLUSION: Normal weight black and white females with comparable family histories of obesity exhibit dissimilar metabolic responses during rest, exercise and recovery. Lower rates of oxygen consumption, higher metabolic reliance on carbohydrate, and higher levels of insulin may slowly impact energy balance predisposing these black females toward the eventual onset of obesity.