The current epidemic of obesity has occurred despite the existence of ? a body weight regulatory system which, for most of mankind's history, ? has matched energy intake with energy expenditure sufficiently to avoid ? obesity. This suggests that the primary cause of the current obesity ? epidemic is not genetic, but may be due to an environment in which the ? energy balance regulatory system cannot function with sufficient ? precision to keep the population lean. In this application, we propose ? research aimed at understanding how factors in the environment, namely ? high fat/energy dense diets and physical inactivity, can promote obesity ? by affecting the precision of regulation of energy and fat balance. It ? is our intent to identify dietary and physical activity patterns that ? are associated with increased precision of energy balance regulation and ? which can prevent development of obesity. Laboratory data suggest that ? high fat diets promote obesity by increasing the probability of ? overconsumption of total energy.
Our first aim i s to systematically ? examine the relationship between dietary fat and energy intake across ? a range of diet compositions in sedentary subjects. While this has been ? done for diets with extreme variation in dietary fat (i.e., less than ? or equal to 20 percent vs greater than or equal to 40-60 percent) it has ? not been done for dietary fat content within the range of usual ? consumption of U.S. adults (i.e. 20-40 percent fat diets). We ? hypothesize that this relationship will not be linear and that there ? will be a threshold level or a range of dietary fat associated with ? a low probability of increased energy intake and positive energy ? balance. This information will be useful in developing dietary ? guidelines for obesity prevention.
Our second aim i s to determine how ? level of physical activity interacts with dietary fat content to affect ? the likelihood of developing positive energy balance. We hypothesize ? that the optimum level of dietary fat to minimize the probability of ? positive energy balance will depend on level of physical activity and ? the optimum level of physical activity to minimize the likelihood of ? positive energy balance will vary with dietary fat content. This work ? will be among the first to study the interaction of dietary and physical ? activity patterns in promotion and prevention of obesity. The results ? will help identify the changes required in current dietary and physical ? activity patterns if we are going to be successful in preventing the ? development of obesity. ?
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