The 2 year proposed project is aimed at understanding the patterns of physical activity in a reduced obese population as compared to non -reduced controls. Only a minority of individuals who achieve substantial weight loss are able to succeed at long term weight loss maintenance. Understanding the factors that contribute to prevention of weight regain could aid in the development of strategies to enable more individuals to succeed at weight loss maintenance. Using participants from the National Weight Control Registry, the project will use accelerometers and physical activity questionnaires to determine the amount, type, frequency, intensity and duration of physical activity in a successfully reduced obese population as compared to matched controls. A major hypothesis of this proposal is that the successfully reduced obese sustain a higher level of physical activity, and it is this high level of activity that is a major factor in weight maintenance. In addition, we hypothesize that successfully reduced obese subjects maintain a high degree of self monitoring and will be more likely to accurately report their physical activity. No previous studies have assessed patterns of physical activity in reduced obese subjects.