Effectiveness of Bariatric Surgery for NAFLD/NASH

Inclusion Criteria: \[For Base-NAFLD\] 1. Age between 16 and 65 years (all sexes). 2. Diagnosed with obesity according to the World Health Organization criteria for obesity in Asian populations and scheduled for a primary bariatric surgery at the participating centres. 3. Diagnosed with hepatic steatosis preoperatively by radiologic (including ultrasonography, magnetic resonance imaging \[MRI\]-derived proton density fat fraction \[PDFF\]) or pathologic(intraoperative hepatic pathology) examinations. \[For Base-NASH\] 1. Age between 16 and 65 years (all sexes). 2. Diagnosed with obesity according to the World Health Organization criteria for obesity in Asian populations and scheduled for a primary bariatric surgery at the participating centres. 3. Histologically confirmed NASH with fibrosis: NAFLD activity score(NAS) ≥4 with at least 1 in each single item and NASH-CRN fibrosis stage ≥F1 Exclusion Criteria: * any patient who had previously been submitted to any type of bariatric surgery; * history of excessive drinking: in the past 12 months, the male equivalent of alcohol consumption more than 30g/d, and the female more than 20g/d; * history of taking amiodarone, methotrexate, tamoxifen, glucocorticoids, etc.； * history of specific diseases: Gene type 3 hepatitis C virus (HCV) infection, hepatolenticular degeneration, autoimmune hepatitis, total parenteral nutrition, lack of beta lipoproteinemia, congenital lipid atrophy, celiac disease which causing fatty liver, etc.; * previous major gastrointestinal surgery； * diagnosed or suspected malignancy； * poorly controlled significant medical or psychiatric disorders； * disorders such as a medical history of major pathology; * can not be able to understand and willing to participate in this registry with signature.