Background and Aims: Fatty liver is associated with cardiovascular disease risk factors, but it is not clarified whether variables associated with fatty liver vary between normal weight and overweight/obese individuals. We studied the cross-sectional associations between fatty liver and cardiovascular disease risk factors in 1,999 (mean age 41.9 years, range 34–49) normal weight (N = 863, BMI < 25) and overweight (N = 1,135, BMI ≥ 25) participants of the population-based Cardiovascular Risk in Young Finns Study.

Methods: Liver was scanned by ultrasound and BMI, waist circumference, blood pressure, serum lipids, liver enzymes, glucose, insulin, HbA1c, apoA1, apoB and CRP assessed in clinical examinations and alcohol consumption, physical activity and smoking by questionnaires.

Results: The prevalence of fatty liver was 19% (29% in overweight/obese and 5% in normal weight participants). The independent direct correlates of fatty liver in all participants were

BMI, ALAT, male sex, systolic blood pressure, insulin, apoB, alcohol use and age. Physical activity index was inversely associated. In normal weight participants ALAT, smoking, systolic blood pressure and alcohol use were directly correlated; in the overweight/obese participants ALAT, triglycerides, systolic blood pressure, insulin, CRP and age directly and physical activity index inversely associated. In the interaction analysis alcohol use (P = 0.02), smoking (P = 0.009) and triglycerides (P < 0.0001) were significantly different between overweight/obese and normal weight participants.

Conclusions: Fatty liver was prevalent also in the normal weight young adults. Alcohol use and smoking were independently associated with fatty liver in the normal weight participants. In the overweight/obese participants fatty liver associated with the metabolic syndrome components and CRP.