It is known that a vast majority of patients seeking a bariatric surgery weight reduction procedure have non-alcoholic fatty liver disease (NAFLD), while a smaller subset of patients within this group have a more serious liver problem known as nonalcoholic steatohepatitis (NASH). NASH is a serious liver disease that can lead to cirrhosis, liver failure and ultimately liver transplantation. The purpose of this study is to explore the effects of bariatric surgery on the progression of NASH. The investigators also hope to gain insight into which genes may be responsible for the development of NAFLD and NASH. The knowledge gained from this study will advance the field of fatty liver disease and help design rational treatments to prevent disease progression.