Energy expenditure and free-living physical activity in black and white women: comparison before and after weight loss.
BACKGROUND
The prevalence of obesity is higher in black than in white women. Differences in energy economy and physical activity may contribute to this difference.


OBJECTIVE
The objective of this study was to compare free-living energy expenditure and physical activity in black and white women before and after weight loss.


METHODS
Participants were 18 white and 14 black women with body mass indexes (in kg/m(2)) between 27 and 30. Diet, without exercise, was used to achieve a weight loss of >/=10 kg and a body mass index <25. After 4 wk of energy balance in overweight and normal-weight states, body composition was assessed by using a 4-compartment model, sleeping and resting energy expenditures were assessed by using a chamber calorimeter, physiologic stress of exercise and exercise economy were measured by using standardized exercise tasks, and daily energy expenditure was assessed by using doubly labeled water.


RESULTS
Weight loss averaged 12.8 kg. Sleeping and resting energy expenditures decreased in proportion to changes in body composition. Weight reduction significantly improved physiologic capacity for exercise in both groups of women, making it easier for them to be physically active. Black women had lower body composition-adjusted energy requirements than did white women-both before and after weight loss-during sleep (9% lower, 519 kJ/d; P < 0.001), at rest (14% lower, 879 kJ/d; P < 0.001), during exercise (6% lower; P < 0. 05), and as a daily total (9% lower, 862 kJ/d; P < 0.06). By contrast, free-living physical activity was similar between the groups.


CONCLUSIONS
Weight-reduced women had metabolic rates appropriate for their body sizes. Black women had lower resting and nonresting energy requirements in both overweight and normal-weight states than did white women and did not compensate with greater physical activity, potentially predisposing them to greater weight regain.
Weinsier
R L
RL
Departments of Nutrition Sciences, Human Studies, Biostatistics and Biomathematics, and Critical and Diagnostic Care and the General Clinical Research Center, the University of Alabama at Birmingham, 35294, USA. weinsier@shrp.uab.edu
Hunter
G R
GR
Zuckerman
P A
PA
Redden
D T
DT
Darnell
B E
BE
Larson
D E
DE
Newcomer
B R
BR
Goran
M I
MI
D015502:Absorptiometry, Photon; D000328:Adult; D001741:Black or African American; D001823:Body Composition / Q000502:physiology; D015992:Body Mass Index; D001834:Body Water; D015519:Bone Density / Q000502:physiology; D002153:Calorimetry, Indirect; D003903:Deuterium / Q000652:urine; D004038:Diet, Reducing; D004734:Energy Metabolism / Q000502:physiology*; D015444:Exercise / Q000502:physiology; D005260:Female; D006801:Humans; D008019:Life Style; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D008954:Models, Biological; D009765:Obesity / Q000208:ethnology / Q000378:metabolism / Q000503:physiopathology*; D010085:Oxidative Phosphorylation; D010101:Oxygen Consumption / Q000502:physiology; D010103:Oxygen Isotopes / Q000032:analysis; D010809:Physical Fitness; D015431:Weight Loss / Q000502:physiology*; D044465:White People
D010103:Oxygen Isotopes; D003903:Deuterium