BACKGROUND: Little is known about dietary habits and their relationships with liver disease in nonalcoholic fatty liver disease (NAFLD) patients, particularly in the absence of obesity, diabetes or hyperlipidemia. OBJECTIVE: To assess the association between soft drink consumption and the presence of fatty liver in NAFLD patients who do not have classic risk factors. METHODS: Three hundred ten patients with NAFLD diagnosed by ultrasound were assessed for 36 months in a cross-sectional manner. Thirty-one patients (10%) who had NAFLD without classic risk factors were compared with 30 healthy controls. Physical activity was assessed during the preceding week and year, and every six months for 36 months. Data on daily dietary intake of food and soft drink, and the source of added sugar were collected during two seven-day periods, at the beginning of the study, and within two weeks after the metabolic tests by using a validated food questionnaire given by a trained dietician. Insulin resistance and lipid peroxidation were assessed by homeostasis model assessment-insulin resistance index (HOMA-IRI) and malondialdehyde (MDA) levels, respectively. RESULTS: Eighty per cent of patients (25 of 31) consumed an excessive amount of soft drink beverages (more than 50 g/day of added sugar) for 36 months, compared with 20% in healthy controls (P<0.001). Twenty per cent of patients consumed one drink per day, 40% consumed two to three drinks per day, and 40% consumed more than four drinks per day for most days during 36 months. The most common soft drinks consumed were regular Coca-Cola (40% of patients), Diet Coke (40%) and flavoured fruit juices (20%). Ultrasound findings revealed mild fatty liver in 44% of cases (n=14), moderate fatty liver in 38% (n=12), and severe fatty liver in 18% (n=5). HOMA-IRI and MDA levels were significantly higher in patients with NAFLD than in healthy controls (HOMA-IRI, 3.7 versus 1.7, P<0.001; and MDA, 420±300 μmol/mL versus 200±100 μmol/mL; P<0.001). When controlled for other factors, including dietary composition and physical activity, soft drink beverage consumption was the only independent variable that was able to predict the presence of fatty liver in 82.5% of cases with a sensitivity of 100%, a specificity of 76%, a positive predictive value of 57% and a negative predictive value of 100%. CONCLUSION: The present study may add important insight into the role of sugar-sweetened beverage consumption as a cause of fatty liver in patients without risk factors. Patients are encouraged to change their long-standing drinking behaviour.