The prevalence of Non-alcoholic fatty liver disease (NAFLD) in individuals with T2DM can be as high as 70%, and these patients experience a twofold increased risk of all-cause mortality. In patients with severe obesity, the prevalence of NAFLD may rise to 90%. Consequently, the prevalence of NAFLD represents a significant global health burden that requires urgent clinical attention and management. NAFLD is explicitly defined by the presence of excessive hepatic fat accumulation in the absence of other causative factors, which include, but are not limited to, significant alcohol consumption, viral hepatitis, the use of steatogenic medications such as amiodarone or tamoxifen, and concurrent liver diseases. This book discusses several topics highly correlated with NAFLD, including nutrition, micronutrients, gut microbiota, diet, metabolic disease, pregnancy, and lifestyle factors, to enhance the general public’s comprehensive understanding of NAFLD.