Effects of Dietary Intervention and Surgery on NAFLD (Non-Alcoholic Fatty Liver Disease)

Effects of Dietary Intervention and Surgery on NAFLD (Non-Alcoholic Fatty Liver Disease)

Approximately 90% of people undergoing bariatric surgery have NAFLD, which is a condition where fat accumulates in the liver and can lead to inflammation and scarring. It mostly causes no symptoms, however, in the most advanced cases there is an increased risk of liver cancer or liver failure.

NAFLD is currently managed by weight loss and treating associated diseases such as diabetes. No medicines have been licensed to directly treat it but bariatric surgery has been shown to be usually beneficial, although it is unknown whether some operations are better than others. It is also unclear whether this is due to general weight loss or other factors.

This study will be conducted in a hospital setting and aims to determine what changes in liver fat and fat processing occur after pre-operative low calorie diet and the two most common types of bariatric surgery (Roux-en-Y Gastric Bypass and Sleeve Gastrectomy.

Participants will have ten study visits, four of which may be combined with NHS appointments. Participants will undergo investigations including MRI scans to measure changes in NAFLD and DEXA scans to measure changes in fat and fat-free mass (FFM). Participants will also undergo mixed meal testing to which stable isotopes (deuterated water and 13c-palmitate) will be added to allow changes in fat processing to be detected. In addition to samples taken as part of NHS care, blood, urine, liver and fat (visceral and subcutaneous (abdominal and gluteal)) will be used for research. Visits will take place before and after low calorie diet and bariatric surgery.

Inclusion Criteria:

• Bariatric surgery is already planned for the participant
• Participant is willing and able to give informed consent for participation in the study.
• Aged ≥18 or ≤75 years.
• Body Mass Index ≥35 ≤55 kg/m2

Exclusion Criteria:

• Contraindication to MRI
• Prior or current participation in a CTIMP that could affect study results
• History of alcoholism or a greater than recommended weekly alcohol intake (14 units per week)
• History of albumin allergy
• Anticoagulant treatment
• Pregnant or nursing mothers
• Type 2 Diabetes
• A liver disease other than NAFLD
• Histological confirmation of lack of NAFLD on liver biopsy
• Large hiatus hernia (that would prohibit Sleeve Gastrectomy)
• Active gastrooesophageal reflux disease (that would prohibit Sleeve Gastrectomy)
• Active malabsorptive intestinal disease (that would prohibit Roux-en-Y Gastric Bypass surgery)