Background: Physical exercises are the first step of therapy for people with non-alcoholic fatty liver disease (NAFLD). Objective: The purpose of this meta-analysis is to evaluate the efficacy of aerobic exercise training with or without diet to ameliorate liver function, insulin resistance, and lipids in adults. Data sources: We searched relevant databases up to 10 June 2021 for conducting a systematic review and meta-analysis of controlled trials lasting 4 or more weeks that investigated the effects of aerobic exercise alone or accompanied by diet on change in liver enzymes, intrahepatic fat (IHF), insulin resistance, and lipids. Results: Sixteen studies including 2255 participants were included. There was a significant pooled weighted mean differences (MD) for the comparison between aerobic exercise versus control in alanine aminotransferase (ALT; p = 0.003), aspartate aminotransferase (AST; p = 0.006), IHF (p = 0.0004), body mass (p = 0.0003), and body mass index (p = 0.004). Moreover, there was a significant pooled MD for the comparison between aerobic exercise plus diet versus control in ALT (p < 0.0001), AST (p = 0.01), IHF (p = 0.02), GGT (p < 0.00001), insulin (p < 0.0001), HOMA-IR (p < 0.00001), body mass (p < 0.0001), and BMI (p = 0.01). Conclusion: Our findings demonstrate a role for aerobic exercise with and without diet protocol as a therapeutic purpose, and suggest that evaluation of aerobic training levels and aerobic training prescription plus diet should be routine in NAFLD. Keywords: NAFLD; aerobic exercise; diet; insulin resistance; intrahepatic fat.