Disclosure: The authors declare no conflict of interest. 2 Abstract Purpose of review: To discuss the influence of obesity, insulin resistance, type 2 diabetes (T2D) and non-alcoholic fatty liver disease (NAFLD) on bile acid (BA) metabolism and analyze whether these findings reinforce current beliefs about the role of BAs in the pathophysiology of these diseases. Recent findings: Discordant results on plasma BA alterations in NAFLD patients have been reported. Obesity, insulin resistance and T2D, common co-morbidities of NAFLD, have been associated with BA changes, but the individual BA species variations differ between studies (summarized in this review), perhaps due to clinico-biological differences between the studied patient populations and the heterogeneity of statistical analyses applied. Summary: The regulatory role of BAs in metabolic and cellular homeostasis render BAs attractive candidates as players in the pathophysiology of NAFLD. However, considering the complex