The long-term objective of this proposal is to apply information gained from laboratory studies of the variables that control food intake to the treatment of obesity. We plan four types of studies. 1) We will study the microstructure of eating behavior in the laboratory by electromyographic recording of chews from the masseter muscle. These studies will show how chews, one of the biological units of eating behavior, determine the rate of food intake. We will evaluate the effect of major variables such as palatability of food on chewing patterns and how chewing patterns can be modified to change ingestion rate. 2) The EMG recording of chews will also be also be used to validate an intraoral sensor which we are developing for ambulatory monitoring of chews in the natural environment. We will use ambulatory monitoring of chews to study daily meal patterns in lean and obese subjects and in patients during treatment for obesity. Analysis of these meal patterns will help us to understand how meal size and meal frequency are controlled and will help us to identify problem eating patterns in obese patients. 3) We will continue laboratory studies to examine the variables that contribute to the different eating patterns between lean and obese women that we have observed previously. We will also test whether behavioral changes that are advocated by treatment programs for obesity, such as slowing the rate of ingestion, actually help people to eat less. 4) We will draw on a battery of tests that differentiate the eating behavior of lean and obese people to monitor the progress of patients before, during, and after treatment for obesity. We will examine whether our behavioral measures are related to other physiological and psychological measures on the patients (e.g. resting energy expenditure and scores on the Stunkard-Messick Eating Inventory). We will determine whether our behavioral measures help predict the outcome of treatment and whether certain behavioral changes can either promote or interfere with weight loss. We will also test whether weight loss causes changes in the behavioral measures. Given the fact that most of the people will lose weight regain all or much of it, it is extremely important to optimize the treatment of obesity by tailor-making weight loss regimens to individual patients. This we hope to do on the basis of the data we collect in laboratory tests and in ambulatory monitoring of daily eating patterns by objective means. We also hope to monitor compliance to treatment regimens with ambulatory recording of food intake. It may also be possible in the future to use this system to signal obese patients when they eat too fast, too much, and too often.