**Background:** Non-alcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease globally, with a disease spectrum ranging from simple steatosis to non-alcoholic steatohepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma. NAFLD is closely associated with obesity, metabolic syndrome, dyslipidemia, and type 2 diabetes. The pathogenesis involves insulin resistance, impaired lipid metabolism, inflammation, oxidative stress, and gut microbiota dysregulation. Both genetic polymorphisms and environmental factors (diet, sedentary lifestyle, sleep disorders) modulate NAFLD risk and progression. Importantly, NAFLD and cardiovascular disease (CVD) share common risk factors and pathophysiological mechanisms, including insulin resistance, endothelial dysfunction, and a procoagulant state. Currently, no pharmacotherapy has a specific indication for NAFLD, making lifestyle modification—particularly weight loss, physical activity, and dietary intervention—the cornerstone of management. Major clinical guidelines from the American Association of Clinical Endocrinology, the European Association for the Study of the Liver, the European Society for Clinical Nutrition and Metabolism, the Asian Pacific Association for the Study of the Liver, and the American Gastroenterological Association all recommend the Mediterranean diet for NAFLD patients. Weight loss of >5% provides cardiometabolic benefits and reduces liver fat, while ≥10% weight loss may reverse steatohepatitis and fibrosis.
**Methods:** This is a narrative review summarizing evidence from observational studies, randomized controlled trials, and meta-analyses on the effects of different dietary patterns on NAFLD incidence and progression. The authors searched relevant literature and also queried ClinicalTrials.gov and EudraCT for ongoing trials using the terms "NAFLD" and "Diet." The review covers the Mediterranean diet, low-fat diet, Dietary Approaches to Stopping Hypertension (DASH) diet, vegetarian diets, low/very low-carbohydrate ketogenic diets, and intermittent fasting.
**Key Results:** For the Mediterranean diet, observational studies consistently show inverse associations with NAFLD. In the cross-sectional analysis of the UK Fenland Study and Swiss CoLaus Study (nearly 14,000 participants), higher adherence to the Mediterranean diet was associated with lower prevalence of hepatic steatosis (OR: 0.86; CI: 0.81–0.90). The ATTICA prospective cohort study (n=3,032) found an inverse association between Mediterranean diet adherence and NAFLD (OR: 0.53; CI: 0.29–0.95). In a 6-week randomized crossover trial (n=12), the Mediterranean diet reduced liver steatosis compared to a low-fat-high-carbohydrate diet (39±4% vs. 7±3%; p=0.012). A meta-analysis by Akhlaghi et al. (n=17,095) showed a trend for NAFLD improvement with the Mediterranean diet (OR: 0.95; CI: 0.9–1; p=0.05), with improvements in BMI (effect size −1.23 kg/m²; CI: −2.38 to −0.09), triglycerides (effect size −33.01 mg/dL; CI: −52.84 to −13.18), and insulin resistance (effect size −0.94; CI: −1.29 to −0.58). Haigh et al.'s meta-analysis (n=3,037) found that Mediterranean diet with calorie restriction reduced ALT (p<0.001), AST (p=0.004), fatty liver index (p<0.001), and liver steatosis (p=0.02). For the DASH diet, a case-control study (n=306) showed participants in the highest quartile of DASH score had a 30% reduction in NAFLD risk (OR: 0.70; 95% CI: 0.61–0.80). The Multiethnic Cohort reported an inverse association between DASH scores and NAFLD risk (OR: 0.78; CI: 0.69–0.89). A single 8-week RCT (n=60) found DASH diet improved weight, liver enzymes (p<0.05), triglycerides (p=0.04), insulin resistance (p=0.01), and inflammatory markers (p<0.05). For vegetarian diets, a cross-sectional study (n=3,400) found vegetarians had lower NAFLD risk (OR: 0.79; p<0.05). A 3-month RCT (n=75) showed a lacto-ovo-vegetarian diet improved NAFLD grade compared to standard weight-loss diet (67% vs. 21%; p=0.01). For low/very low-carbohydrate ketogenic diets, a 2-month RCT (n=39) found a very low-calorie ketogenic diet reduced weight (−9.7 kg vs. −1.67 kg; p<0.0001) and liver fat (4.77 vs. 0.79; p<0.005) more effectively than a low-calorie diet. For intermittent fasting, a prospective observational trial (n=697) showed periodic fasting improved fatty liver index (non-T2DM: −14.02, p<0.0001; T2DM: −19.15, p<0.001). A meta-analysis of 6 trials (n=417) showed intermittent fasting improved weight (−2.45%; CI: −3.98 to −0.91; p<0.05) and liver enzymes (ALT: −10.54, CI: −14.01 to −7.08; p<0.05; AST: −11.31, CI: −14.3 to −8.32; p<0.05).
**Clinical Implications:** The Mediterranean diet has the strongest and most consistent evidence for NAFLD management and is the only dietary pattern included in major scientific society guidelines. Weight loss of 5–10% over six months should be a primary goal for overweight or obese patients. Moderate calorie restriction (500–1000 kcal/day) can be achieved through various dietary patterns. The DASH diet, vegetarian diets, low-carbohydrate/ketogenic diets, and intermittent fasting show promise but require more robust RCT evidence. Clinicians should consider patient preferences, comorbidities, and the specific metabolic effects of each diet when prescribing individualized dietary plans. Long-term adherence remains a critical challenge, and combining dietary intervention with pharmacotherapy may be necessary in advanced or non-responsive cases. Factors modulating dietary adherence—including socioeconomic status, age, marital status, and nutrition knowledge—must be addressed to optimize outcomes.