Physiological responses to weight-loss intervention in inactive obese African-American and Caucasian women

The physiological responses of inactive obese premenopausal African-American and Caucasian women to the identical exercise training and behavior modification program were compared.

Inactive obese (96.1+/- 2.9 kg, BMI=34.8 +/- 0.7 kg/m2, % body fat=46.0 +/- 0.8; mean +/- SEM) premenopausal (36 +/- 2 yrs) African-American (n=10) and Caucasian (n=19) women were included. Resting metabolic rate (RMR), respiratory exchange ratio (RER), and maximal aerobic power (VO2max) were measured by indirect calorimetry, and body composition by plethysmography. Resting and maximal heart rates, blood glucose and lipids, and blood pressure were also measured. Treatment consisted of a 13-week diet and exercise behavior modification program. Group mean comparisons were made with a Student's "t"-test or an ANCOVA, which controlled for individual differences in body mass and lean body mass (LBM). Significance was set at p<0.05.

Initially, the groups were not significantly different in height, mass, BMI, age, % body fat, fat mass, LBM, girth measurements, RMR, RER, VO2max, blood pressure, or cholesterol profile. The number of weeks completed, number of exercise sessions completed, total minutes of exercise for the entire intervention, average minutes of daily exercise, and total estimated exercise energy expenditure were all similar between groups. Furthermore, both groups reported similar dietary compliance. Both groups reduced body mass, BMI, LBM, girth measurements, and increased VO2max (mlO2 x kg-1 x min-1) significantly and similarly.

African-American and Caucasian women respond the same physiologically to weight loss intervention. The higher prevalence in obesity for African-American women is not due to a different physiological response to diet and exercise.