INFLUENCE OF DIETARY FATTY ACID COMPOSITION ON TIME-COURSE OF DIET ADAPTATION

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The number of obese people in the U.S. has become a serious public health problem. Currently, two-thirds of adult American women are overweight and roughly half of these are obese. This excess weight increases the risk of early death from chronic disease such as cardiovascular disease, stroke, diabetes mellitus, osteoarthritis, and certain cancers. Two of the causes of obesity are a sedentary lifestyle and a high-fat diet. A sedentary lifestyle leads to reduced daily energy expenditure and a slow increase in fat oxidation during a period of days when the subject is eating a high-fat diet. We think, however, this varies depending on the type of dietary fat. Diets high in monounsaturated fat, the type found in olive oil, should result in greater fat oxidation than diets high in saturated fat, the type found in meats and dairy. Healthy and overweight male and female subjects will be studied for six days each on four different occasions. Each occasion will differ in the type of dietary fat and exercise treatment. These are: (1) diet high in saturated fat with energy expenditure of 1.4 times resting metabolic rate; (2) diet high in saturated fat with about 1 hour of moderate intensity bike riding to increase energy expenditure to 1.8 times resting metabolic rate; (3) diet high in monounsaturated fat with energy expenditure of 1.4 times resting metabolic rate; (4) diet high in monounsaturated fat with 1 hour of moderate bicycle exercise to increase energy expenditure to 1.8 times resting metabolic rate. We will measure 24h macronutrient oxidation using whole room indirect calorimetry and urinary nitrogen analysis on days 1,2,3 and 5 of the protocol, and will measure blood appetite hormones, satiety, and palatibility on day 4 of the protocol. We expect that the increase in fat oxidation on the high fat diet will be greater with a high monounsaturated fat diet compared to a high saturated fat diet, and greater with exercise compared to rest .