Project Number: 1235-51530-007-00
Project Type: Appropriated

Start Date: Feb 16, 2004
End Date: Feb 15, 2009

Objective:
Determine the impact of an increase in physical activity level (PAL) on daily energy expenditure, long-term voluntary food intake, food selection and macronutrient. Identify differences in response to exercise between genders. Identify the changes in physiological markers of food intake, energy metabolism, and risk of chronic disease associated with an increase in PAL.

Approach:
In a crossover design, daily activity levels of male and female volunteers will be altered through a daily exercise intervention of approximately 60 minutes of walking 6 times per week for 14 weeks. Food selection and energy intake of subjects, will be determined by a combination of cafeteria-style feeding, controlled portion consumption and duplicate meal collection. Energy expenditure, macronutrient balance and PAL will be determined through a combination of doubly labeled water, indirect calorimetry and ambulatory monitoring of physical activity. Changes in weight, lean body mass and body fat content will be used as an indicator of energy balance. Fasting and meal challenged levels of insulin, leptin, ghrelin, cortisol and a variety of metabolites will be determined. These values will be correlated to previous and subsequent energy and macronutrient intake and energy balance. In addition, markers of chronic disease, such as blood pressure and blood lipids, will be determined and compared to values obtained during the baseline period.