The study investigates non-alcoholic fatty liver disease from serial liver biopsies collected from participants referred for assessment of bariatric surgery, RYGB or SG.

Non-alcoholic fatty liver disease (NAFLD) is an increasing health care problem closely related to obesity and has become the most common cause of chronic liver disease in developed countries. Today, bariatric surgery is the most efficient treatment of morbid obesity in terms of a rapid and sustained loss of weight. In addition, bariatric surgery is accompanied by improvement of weight-related comorbidities including features of the metabolic syndrome and possibly regression of the entire NAFLD spectrum.

The study is designed as an observational study including 40 patients referred to laparoscopic bariatric surgery (either RYGB or SG). The primary endpoint is change in NAFLD activity score (NAS) in serial liver biopsies collected from participants. Additional tests include blood samples, anthropometry measurements, Fibroscan and full body dual-energy X-ray absorptiometry (DEXA) scan performed together with each biopsy.

This unique model of serial liver biopsies in morbidly obese patients referred to bariatric surgery (RYGB or SG), combined with state-of-the-art technologies and bioinformatics, will provide important information about the effects of weight loss on NASH. The results will improve our understanding of the underlying mechanisms with the potential of identifying new potential NASH targets or diagnostic biomarkers.

Inclusion Criteria:

• Obese (BMI≥35 kg/m2) individuals referred for bariatric surgery, either RYGB or SG
• Age between 18 and 60 years at the time of inclusion
• Evidence of potential NASH with fibrosis
• Willing to give informed consent and comply with all study procedures

Exclusion Criteria:

• Type 1 diabetes
• Alcohol consumption ≥20 g/day for women or ≥30 g/day for men over a two-year period prior to inclusion
• Clinically significant kidney function impairment or other laboratory findings at time of screening leading to the diagnosis of clinically relevant disorders
• Any physical or psychological condition that the investigator evaluates would interfere with trial participation
• Previous gastrointestinal surgery (excluding cholecystectomy and appendectomy)
• Planned elective surgery (other than bariatric surgery) during the study period with the exception of dermatosurgical, ENT (ear, nose, throat) or dental procedures not requiring general anaesthesia and/or perioperative antibiotic treatment
• Pregnancy or desire to become pregnant during the study period
• Any ongoing medication that the investigator evaluates would interfere with trial participation including anticoagulant medication, and medication that could cause NAFLD
• Contraindications to liver biopsy
• Other causes of liver disease than NAFLD, including viral hepatitis, Wilsons disease, cystic fibrosis, coeliac disease and alpha-1 antitrypsin deficiency.

30-40 patients referred to laparoscopic bariatric surgery (either RYGB or SG)