Non-alcoholic Fatty Liver Disease in Morbidly Obese Individuals Undergoing Bariatric Surgery: Prevalence and Effect of the Pre-Bariatric Very Low Calorie Diet

Non-alcoholic fatty liver disease (NAFLD) affects 75 to 100% of the patients undergoing bariatric surgery (BSx), with non-alcoholic steatohepatitis (NASH) being present in 24 to 98% of the patients. We do not know whether these rates were before or after a very low calorie diet (VLCD) often prescribed before laparoscopic BSx and what is the prevalence of NAFLD post-VLCD. The purpose of this study is to determine the prevalence of simple steatosis (SS) and NASH in obese individuals undergoing BSx post-VLCD and assess biochemical markers pre- and post-VLCD in a subgroup of patients. One hundred and thirty-nine patients undergoing BSx at a single Canadian bariatric program had biochemical and clinical variables collected pre-VLCD. In 21 patients, biochemical measurements were repeated post-VLCD. During BSx, a wedged liver biopsy was performed in all patients and histology was reported as normal liver (NL), SS, or NASH. NAFLD was diagnosed in 76.3% of the BSx patients with 61.9% having SS and 14.4% having NASH; 23.7% had NL. Those with NASH had significantly higher (p < 0.05) pre-VLCD ALT, AST, insulin resistance, and proportion of individuals with diabetes compared to those with NL. Overall, VLCD resulted in significant decreases in BMI, ALP, fasting glucose and insulin, HbA1c, total cholesterol, HDL and LDL cholesterol, and significant increases in AST and ALT. Changes were similar between groups. Post-VLCD, the prevalence of NAFLD and NASH was lower compared to published reports, with almost 25% of the patients having a NL. With VLCD, metabolic and clinical changes were similar between the three groups suggesting that pre-VLCD factors may affect liver histology.