OBJECTIVETo determine the effect of body mass index (BMI) at baseline and its change during follow-up on the incidence of non-alcoholic fatty liver diseases (NAFLD) in apparently healthy adults.

METHODSSubjects free of previous liver injury, alcohol consumption of more than 140 g/week and hepatitis B virus infection were identified from employees of Shanghai BaoSteel Group who underwent voluntary medical checkups at a 2-year interval. The analyzed population consisted of 5402 non-drinking subjects (4633 men) of age 36.5+/-9.3 years (18-65 years), who had normal livers at baseline. Among them 327 subjects (6.05%) developed fatty liver in 2 years. Those who developed NAFLD showed advanced age (especially in females), elevated BMI, high levels of serum triglyceride and total cholesterol, high prevalence rates of obesity, hyperlipidemia, hypertension and hyperglyceridemia at baseline, more weight gain and increase of serum triglycerides during the 2-year period. The incidence of NAFLD increased significantly with the changes of BMI at baseline, from 1.4% in subjects with normal weight, 6.4% in overweight, 16.8% in obese patients to 24.5% in severe obesity (Chi2 test = 389.01, P = 0.000 in trend analysis). Logistic regression analysis showed a significant interaction occurred between NAFLD age, BMI and serum triglyceride at baseline, and subtle gain of BMI and triglyceride during follow-up.

CONCLUSIONSThere is a high incidence of NAFLD in a Chinese workplace. Obesity and related metabolic disorders at baseline, and more weight gain and increased serum triglyceride during follow-up are important predictors for the development of NAFLD.