Nonalcoholic Fatty Liver Disease and Bariatric Surgery

Sindu Stephen; Ancha Baranova; Zobair M Younossi


Expert Rev Gastroenterol Hepatol. 2012;6(2):163-171. 

In This Article

Abstract and Introduction


Nonalcoholic fatty liver disease (NAFLD) is one of the most common causes of chronic liver disease worldwide. Treatment recommendations for NAFLD are aimed towards weight reduction, thereby reducing insulin resistance. Unfortunately, lifestyle modifications have not yielded long-term success, while durable weight loss is routinely achieved with bariatric surgery. This article reviews the effects of bariatric surgery on patients with NAFLD. In these patients, postsurgical evaluations of liver histology by repeat liver biopsy are hindered by the risk of the procedure and the inherent sample variability, which makes the impact of bariatric surgery on NAFLD difficult to quantify. In longitudinal studies of NAFLD, the biopsy-based evaluations should be augmented by repeated measurements of the noninvasive biomarkers that may provide an insight into the changes in the physiological state of the liver after bariatric or other types of interventions. Nevertheless, currently available tests are not able to provide this type of in-depth outcome measures for these patients.


Currently, the WHO estimates more than 1 billion people worldwide to be overweight, of whom at least 300 million are obese. The prevalence of nonalcoholic fatty liver disease (NAFLD) in morbidly obese patients can range from 75 to 100%.[1] It affects up to 30% of the US population and is one of the most common types of liver disease worldwide.[2] Metabolic syndrome and insulin resistance are associated with obesity and may be risk factors for increased liver-related mortality in NAFLD patients.[3]

Nonalcoholic steatohepatitis (NASH) is a progressive subtype of NAFLD affecting 3.5–5% of the US population.[4] This prevalence rate increases with risk factors such as obesity and Type 2 diabetes and can be as high as 20% in patients undergoing bariatric surgery. Currently, there are no validated noninvasive biomarkers to diagnose NASH. Steatohepatitis remains a histological diagnosis, characterized by hepatic steatosis, lobular inflammation and hepatocellular ballooning.[5] Up to 15–20% of patients with histologically proven NASH may progress to cirrhosis.[6]

The association between NAFLD and obesity makes weight loss a plausible treatment strategy in NAFLD patients. Substantial weight loss has been shown to have a significant benefit, but most patients fail to achieve a meaningful decrease in BMI with diet and exercise. Bariatric surgery provides the only reliable method of achieving weight loss in severe obesity and has been increasingly available for obese patients with NAFLD.[7]


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