 This study will investigate the direct effects of rimonabant ie independent of weight loss in a 2 group randomised study. One group will receive rimonabant for 12 weeks and the other group will have a dietary intervention to match the weight loss in the rimonabant group. Measurements of energy expenditure using indirect calorimetry and Actiheart monitors,fatty acid and triglyceride metabolism using stable isotope techniques and body fat distribution by magnetic resonance imaging will be made before and after the intervention. To determine the possible mechanisms of the changes in metabolism, gene expression of key regulators of fatty acid metabolism in adipose and muscle tissue and circulating levels of adipokines will be measured. 