Weight change and resolution of fatty liver in normal weight individuals with nonalcoholic fatty liver disease

Objectives Obesity is a well-known risk factor for nonalcoholic fatty liver disease (NAFLD), and weight reduction is primarily recommended for managing the disease. However, some NAFLD patients have a normal weight (lean NAFLD), and whether weight reduction is also recommendable for lean NAFLD patients remains unclear. Methods We conducted a longitudinal study of 16 738 adults (average age, 50.5 years; lean NAFLD, 2383 participants) with NAFLD at baseline who underwent repeated health check-up examinations, including bodyweight measurements and abdominal ultrasonography from January 2003 through December 2013. Results During 68 389 person-years of follow-up (median follow-up of 3.00 years), 5819 patients had a fatty liver resolution. Compared with participants who had no weight reduction or increased weight, the fully adjusted hazard ratios for fatty liver resolution in participants with 0-4.9, 5-9.9 and 10% or more weight reduction were 1.67 [95% confidence interval (CI), 1.57-1.77], 3.36 (95% CI, 3.09-3.65) and 5.50 (95% CI, 4.83-6.27), respectively. The association between weight reduction and the fatty liver resolution was stronger in overweight/obese NAFLD participants but was also evident in lean NAFLD participants in a dose-dependent manner. In spline regression models, the association between weight change and the fatty liver resolution was linear among participants with normal weight. Conclusion There was a dose-dependent association between weight reduction and fatty liver resolution in both lean and overweight/obese NAFLD patients. This finding suggests weight reduction as a primary recommendation for lean NAFLD patients as in overweight/obese NAFLD patients.