Comparisons of physical activity and dietary components in an overweight/obese population and their normal weight controls matched for gender, age and height

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Davis, Jaimie Nicole

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The objectives of this study were: 1) to assess differences in voluntary physical activity and dietary components between an overweight/obese population and normal weight matched controls; 2) to assess the accuracy of commonly used activity factors, i.e., indices that represent physical activity in predictive equations for energy, established by the World Health Organization (WHO) and the Institute of Medicine (IOM) in the Dietary Reference Intakes (DRIs). Adults, aged 19-69 years, 53 overweight/obese and 53 normal weight subjects matched for gender, age (± 1 year) and height (±1 inch) were recruited from the local area and university community. Diets were assessed by the Block 60-item food frequency questionnaire, physical activity by the Yale Physical Activity Survey, and body composition by the dual energy X-ray absorptiometry. Resting energy expenditure was obtained by indirect calorimetry and later multiplied by a conversion factor to yield basal energy expenditure. A sub-sample of 62 adults, 31 in each group, wore an accelerometer, an instrument that detects body movement, for seven consecutive days. Accelerometer data showed that overweight/obese adults were less physically active, expended fewer kilocalories per kilogram of body weight, recorded fewer accelerometer counts throughout the week, and spent less time in moderate or greater intensity activity than their normal weight controls. Overweight/obese subjects consumed more total fat, saturated fat and cholesterol and less carbohydrate, complex carbohydrate and dietary fiber than controls. Reported intakes of dietary fiber and carbohydrate were inversely related to percent body fat with and without controlling for potential confounding factors, i.e., age, gender, physical activity-related energy expenditure and other macronutrients. Activity factors derived from accelerometers were significantly lower than those determined by the WHO and DRI methodology for normal but not overweight/obese subjects, suggesting that energy needs for many adults may be overestimated by using these prediction equations. In summary, limited physical activity-related energy expenditure, especially time spent in moderate intensity or greater activity, diet composition, especially low dietary fiber, and overestimation of energy needs by current prediction methodology are implicated in the etiology of obesity. These findings indicate areas of interest for future research and program development aimed at weight management and obesity prevention.