Aim: Prevalence of fatty liver is increasing. In this study, to elucidate the factor that contributes most to recent increases in prevalence of fatty liver, we determined the independent predictors for the onset of fatty liver and compared these predictors between 2000 and 2005.
Methods: Japanese persons, aged 30–74 years, who participated in regular health checks at Kagoshima Kouseiren Medical Health Care Center (10 336 persons in 2000 and 11 011 persons in 2005) were enrolled in the study. Diagnosis of fatty liver was performed by ultrasonography. Body fat percentage (BFP) was determined using a bipedal bioimpedance instrument.
Results: The prevalence of fatty liver has increased between 2000 and 2005 in men (33.3 vs 38.5% in 2000 vs 2005, respectively, P < 0.0001), but not in women (21.3 vs 21.0%, P = 0.8101). Logistic regression analysis revealed that both body mass index (BMI) and BFP are independent predictors of fatty liver in both men and women. BMI did not change in either men (23.4 ± 2.9 vs 23.8 ± 3.0 kg/m2, P = 0.0528) or women (22.8 ± 3.1 vs 22.8 ± 3.3 kg/m2, P = 0.9862) during the survey period. In contrast, BFP increased in men (20.6 ± 4.7 vs 22.3 ± 5.0 kg/m2, P = 0.0003), but not in women (27.4 ± 5.5 vs 28.4 ± 5.9 kg/m2, P = 0.3993). There was no significant change in triglycerides and glucose levels.
Conclusion: These results suggest that altered body composition, particularly increased BFP without an increase in BMI, has developed in men and is strongly associated with the increasing prevalence of fatty live amongst Japanese men.