Abstract: Based on the clinical trials and cohort studies in the Chinese population, this paper systematically summarized the association between weight/ body mass index (BMI) and their changes in preventing non-alcoholic fatty liver disease (NAFLD) and its adverse outcomes. The results showed that BMI was positively correlated with NAFLD risk, but for those with NAFLD, BMI was negatively related to the remission of NAFLD and there was a non-linear dose-response relationship between BMI and adverse outcomes. The lean NAFLD group had a higher risk of all-cause death, liver-related death, digestive system tumors, and obesity-related tumors than the overweight or obese NAFLD and lean non-NAFLD group. Additionally, the association between baseline BMI levels and adverse outcomes in NAFLD populations may be affected by other metabolic indicators. After controlling for baseline BMI, most studies suggested that weight loss could reduce the NAFLD risk. However, there is no consistent conclusion on how to control weight to prevent NAFLD because the methods and the time windows to assess BMI changes vary in different studies. Moreover, for those with NAFLD, limited evidence suggested the different relationship between weight loss and different outcomes. Therefore, we call for conducting multi-center cohort and experimental studies to verify the effect of weight control on NAFLD and its related adverse outcomes after considering the heterogeneity of NAFLD, so as to propose precision weight control recommendations.