Physical activity in free-living, overweight white and black women: divergent responses by race to diet-induced weight loss.
BACKGROUND
Black women are at greater risk of obesity than are white women, perhaps because of their lower levels of physical activity.


OBJECTIVE
We compared free-living activity energy expenditure (AEE) in sedentary white and black women (in overweight and normal-weight states) and in never-overweight control subjects.


METHODS
Subjects included 46 women (23 white, 23 black) studied while overweight and after reaching a normal weight and 38 female control subjects (23 white, 15 black). Diet, without exercise training, resulted in a mean weight loss of 13 kg and a body mass index (in kg/m(2)) < 25. Body composition, sleeping energy expenditure, free-living total energy expenditure, and the energy cost of activity and aerobic capacity were assessed before and after weight loss under 4-wk, diet-controlled, weight-stable conditions and in the control subjects. AEE was defined as above-sleep energy expenditure.


RESULTS
No significant racial differences in body composition, before or after weight loss, were found. After weight loss, AEE and aerobic capacity increased in the white women and decreased in the black women (P < 0.05 and P < 0.02, respectively). After weight loss, but not before, the white women had a significantly higher mean AEE than did the black women (2448 +/- 979 and 1728 +/- 1373 kJ/d, respectively; P < 0.05), approximating AEEs in the white (2314 +/- 1105) and black (2310 +/- 1251) control subjects.


CONCLUSIONS
Relative to the responses of the white women to diet-induced weight loss, the black women became less fit and less physically active. Induction of a normal body weight in overweight black women appeared to produce a more obesity-prone state, favoring weight relapse.
D000328:Adult; D044383:Black People; D001823:Body Composition; D015992:Body Mass Index; D004038:Diet, Reducing; D004734:Energy Metabolism; D015444:Exercise; D005260:Female; D006801:Humans; D008019:Life Style; D008875:Middle Aged; D009765:Obesity / Q000178:diet therapy*; D012008:Recurrence; D012890:Sleep / Q000502:physiology; D015431:Weight Loss; D044465:White People