Association between nonalcoholic fatty liver, markers of obesity, and serum leptin level in young adults.

OBJECTIVES: The aim of the present study was to clarify the risk factors for nonalcoholic fatty liver in young adults. METHODS: One thousand two hundred two students, aged 18-21 yr, received matriculation health examinations, including measurements of body mass index and percent body fat and determination of serum levels of ALT at Nagasaki University in 1998. One hundred twenty-nine were found to have borderline or elevated levels of serum ALT, and 105 of the 129 students (75 men and 30 women) were subjected to further analysis for the presence of fatty liver using ultrasonography, by which both the degree of steatosis and the abdominal wall fat index (AFI) corresponding to the ratio of visceral to s.c. adipose tissue (V/S ratio) were evaluated, in addition to determination of the serum level of leptin. RESULTS: Of 105 students, 74 (70%) had fatty liver. The incidence of moderately to severely fatty liver was significantly higher in men than in women. In parameters related to obesity, the close correlation between body mass index and percent body fat was observed in both sexes. The serum level of leptin correlated well with percent body fat and AFI (V/S ratio) in women, whereas it did not correlate with AFI (V/S ratio) in men. Multiple logistic regression analysis indicated that AFI (V/S ratio) was the only independent risk factor for fatty liver in both sexes. CONCLUSIONS: These results suggest that visceral fat distribution is a key risk factor for nonalcoholic fatty liver in young adults.