Public Release: 

Bariatric surgery may resolve liver disease

Study explores the effect of weight loss on NAFLD

American Gastroenterological Association

Bethesda, MD (Dec. 1, 2008) - Obesity is a growing epidemic in the U.S. with a significant increase in prevalence from 15 percent to 32.9 percent from 1980 to 2004. Nonalcoholic fatty liver disease (NAFLD) is an emerging problem related to the obesity epidemic, becoming one of the most common causes of liver disease in the nation.

Bariatric surgery has become a popular and effective method for rapid and permanent significant weight loss in morbidly obese individuals. A recent study reports bariatric surgery results in improvement of histopathological features of NAFLD. Complications of NAFLD, including steatosis, steatohepatitis and fibrosis appeared to improve or completely resolve in a majority of patients after bariatric surgery-induced weight loss, according to results of a study published in Clinical Gastroenterology and Hepatology, an official journal of the American Gastroenterological Association (AGA) Institute.

"Even today, the effect of weight loss after bariatric surgery on the liver, particularly NAFLD, remains unclear. There is a lack of well-defined trials exploring this relationship," said Gagan K. Sood, MD, of the University of Texas Medical Branch and lead author of the study. "Our team assessed and quantified this effect and found encouraging news: a majority of patients experience complete resolution of NAFLD after bariatric surgery, and the risk of progression of inflammatory changes and fibrosis seems to be minimal."

For this meta-analysis, 15 studies were selected for final data extraction. The mean age of the participants at the time of weight loss surgery ranged from 35.6 to 49 years. Mean BMI at the time of weight loss surgery ranged from 43.9 to 56 kg/m2 and the mean BMI at follow-up liver biopsies ranged from 28.6 to 39kg/m2. Percentage reduction in mean BMI values ranged from 19.11 to 41.76.

The pooled proportion of patients with improvement or resolution in steatosis was 91.6 percent, steatohepatitis was 81.3 percent, fibrosis was 65.5 percent and complete resolution of NASH was 69.5 percent.

Generalizability of these results may require confirmation from multi-center, large scale, well designed trials. Future studies need to be done using uniform histopathological criteria for liver biopsy specimens.

NAFLD encompasses a range of conditions involving the liver that affect people who drink little or no alcohol. The spectrum of NAFLD ranges from hepatic steatosis (fat accumulation in the liver cells) to the more severe non-alcoholic steatohepatitis (NASH) and fibrosis that can progress to cirrhosis, end-stage liver disease, and hepatocellular carcinoma. Prevalence of NAFLD is estimated to be around 70 percent in obese individuals and 85 percent to 95 percent in patients with morbid obesity. The prevalence of NASH is as high as 18.5 percent in obese individuals and 33 percent in those who are morbidly obese. The pathophysiologic mechanisms of NAFLD have not been clearly elucidated as yet, but obesity and insulin resistance are considered to be the main causative factors.


About the AGA Institute
The American Gastroenterological Association (AGA) is dedicated to the mission of advancing the science and practice of gastroenterology. Founded in 1897, the AGA is one of the oldest medical-specialty societies in the U.S. Comprised of two non-profit organizations--the AGA and the AGA Institute--our more than 16,000 members include physicians and scientists who research, diagnose and treat disorders of the gastrointestinal tract and liver. The AGA, a 501(c6) organization, administers all membership and public policy activities, while the AGA Institute, a 501(c3) organization, runs the organization's practice, research and educational programs. On a monthly basis, the AGA Institute publishes two highly respected journals, Gastroenterology and Clinical Gastroenterology and Hepatology. The organization's annual meeting is Digestive Disease Week®, which is held each May and is the largest international gathering of physicians, researchers and academics in the fields of gastroenterology, hepatology, endoscopy and gastrointestinal surgery. For more information, please visit

About Clinical Gastroenterology and Hepatology
The mission of Clinical Gastroenterology and Hepatology is to provide readers with a broad spectrum of themes in clinical gastroenterology and hepatology. This monthly peer-reviewed journal includes original articles as well as scholarly reviews, with the goal that all articles published will be immediately relevant to the practice of gastroenterology and hepatology. For more information, visit

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