SIRT1 and fatty liver disease: Although increasing the expression levels of Sirt1, the mammalian orthologue of Sir2, does not extend lifespan, it appears to extend healthspan (Bordone and Guarente, 2005, Herranz et al., 2010), improve insulin sensitivity and protect against hepatic steatosis in transgenic mice (Banks et al., 2008, Bordone et al., 2007, Boutant et al., 2016, Pfluger et al., 2008).