One of the main objectives of this study will be to assess potential differences in important risk factors associated with Metabolic Syndrome in overweight adults who do not participate in a regular exercise program compared with overweight individuals who do exercise regularly. In addition, we will determine the effects of a single, modest session of exercise on the body's ability to control blood sugar and regulate fat metabolism in obese sedentary adults vs. obese adults who live a physically active lifestyle. Our study focuses on identifying mechanisms responsible for improved insulin action related to regular exercise and to provide novel targets for preventing and treating type 2 diabetes.