The investigational drugs administered in this study activate proteins called PPARs. Data in the scientific literature on PPARs, as well as animal data and early clinical data generated by GSK with these drugs, suggest that activation of PPARs may cause the body to increase its use of fatty acids for energy, and lead to a reduction in body fat. There are also data to suggest a role for PPARs in regulating lipid (e.g., cholesterol) levels and inflammation. These and other activities of PPARs are being further explored in this clinical study.