INTRODUCTION: Non-alcoholic fatty liver disease (NAFLD) is a common liver disease characterized by an increase in fat in liver cells. The outbreak of NAFLD is estimated to be 32.4% worldwide, with higher rates in Asia and Iran. Nutritional factors such as excessive calorie intake, high fructose intake, copper deficiency, and increased iron intake play an important role in NAFLD. Since there is no specific treatment for NAFLD, intermittent fasting (IF) diet has been suggested as an alternative treatment for obesity and related complications. Previous studies showed the potential positive effects of IF on metabolic health and the reduction of oxidative stress in NAFLD. This randomized controlled trial (RCT) will be aimed to examine the effect of the IF diet in comparison with a low-calorie diet (LCD) on lipid profile, glycemic status, and liver fibrosis in patients with NAFLD. METHODS AND ANALYSIS: This is a parallel randomized clinical trial conducted on 52 overweight and obese patients with NAFLD. Participants will be randomly assigned to receive either 16:8 IF (fasting from 8 P.M. to 12 P.M. the next day) or a low-calorie (55% carbohydrate- 30% fat, 15% protein) diet for 12 weeks. Anthropometric measurements, liver assessments, and metabolic evaluations will be assessed before and after the intervention. Primary outcomes include liver steatosis and fibrosis, while secondary outcomes include liver function enzymes, insulin resistance, lipid profile, and anthropometric measurements. DISCUSSION: Since obesity and insulin resistance are the most important risk factors of NAFLD, and there is no treatment for it, it seems that lifestyle changes such as low caloric diet like IF and exercise can improve lipid metabolism and liver enzymes. TRIAL REGISTRATION: Iranian registry of clinical trials (IRCT20170202032367N5).