The consequences of pathologic adipose tissue accumulation have been described for almost all organs. Nonalcoholic fatty liver disease (NAFLD) is considered the most relevant hepatic manifestation of obesity. There is great interest in the study of NAFLD, and new insights into its pathogenic process have been described. Currently, in addition to insulin resistance, which was considered the hallmark of this disease, endocrine, immunologic, and central nervous system factors are attracting interest as explanatory variables. In this review, new factors associated with the main theories on the pathophysiology of NAFLD are analyzed.