Grant: Operating Grant

There is little evidence that the rise in obesity observed in recent decades is slowing. Few would argue that it is the environment rather than individual biology that is driving the rapid increase in obesity regardless of age, gender or race. Accordingly, while it is clear that most adults can adopt significant changes in physical activity and diet behavior and achieve substantial weight loss short-tern, forces within the environment make it difficult to sustain dramatic changes in behaviour long-term and thus sustained weight loss, if not weight gain (rebound), is the result. Recently it has been suggested that a strategy of preventing weight gain may be more feasible than a strategy of weight reduction for the entire population and that prevention of weight gain could be achieved in most adults through a small-changes approach to diet and physical activity. Specifically, a 100 kilocalorie change in any combination of increased energy expenditure and decreased energy intake could prevent weight gain in most adults. Although initial evidence suggests that the adoption of small changes in lifestyle behaviors can prevent weight gain over a few months, whether adopting small changes in diet and physical activity can be adopted and sustained for several years in unknown. We will perform a study designed to test the effectiveness of a small-changes approach in diet and physical activity to prevent weight gain long-term (3 years) in overweight and obese adults. Our approach will incorporate established behavior change techniques and proven methods for constructing health messages to encourage ongoing goal setting, planning, and monitoring of healthy lifestyle behavior. It is hoped that the findings of our study will provide a practical option for overweight and obese persons to adopt healthy behaviors long term and prevent weight gain.