This is a prospective, multicenter cohort study, which subjects were obese patients requiring bariatric surgery.

This study aims to explore the the effectiveness of bariatric surgery for NAFLD/NASH with fribrosis, to explore the differences in the effectiveness among sleeve gastrostomy [SG], Roux-en-Y gastric bypass [RYGB], or one anastomosis gastric bypass [OAGB], and to explore the independent effectiveness of bariatric surgery in histological remission of NAFLD/NASH.

The first stage of the cohort was started in 2020, named Base-NAFLD; In May 2024, based on Base-NAFLD, we plan to continue established a secondary cohort, named Base-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.

The study population will comprise male and non-pregnant female patients, aged 16-65years both inclusive, with morbid obesity.