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Obes Res. 2005 Jul;13(7):1180-6.

Roux-en-Y gastric bypass improves liver histology in patients with non-alcoholic fatty liver disease.

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Welch Center for Prevention, Epidemiology and Clinical Research, The Johns Hopkins University, 2024 E. Monument Street, Suite 2-600, Baltimore MD 21205, USA.



Non-alcoholic fatty liver disease (NAFLD) is the most common cause of liver disease in the United States and is prevalent in morbidly obese patients. While weight loss and treatment of risk factors are recommended, the reported effects of bariatric surgery on NAFLD are mixed.


We examined liver histology at the time of Roux-en-Y gastric bypass surgery and at elective incisional hernia repair after weight loss for 16 patients at one center. Slides were read by one pathologist, blinded to clinical data, using the Brunt criteria. Clinical and laboratory data were extracted from chart review. Alcohol use was ascertained by two interviews.


At baseline, the mean age was 44 years, 50% were women, 88% were white, and the mean BMI was 51 kg/m2. None had significant alcohol use. On initial biopsy, all patients showed steatosis, 94% had inflammation, 88% had ballooning degeneration, 88% had perisinusoidal fibrosis, and 81% had portal fibrosis. The mean time between the two biopsies was 305 +/- 131 (SD) days. The mean weight loss was 118 +/- 29 lb. Steatosis improved in 15 of 16 patients, with resolution in 13. Twelve of 15 patients with inflammation at baseline showed improvement, and 12 of 14 showed less ballooning. Six of 14 patients with perisinusoidal fibrosis and 6 of 13 with portal fibrosis showed improvement. No patient had worsening of steatosis, inflammation, ballooning, or fibrosis.


Our study shows improvement in all of the histological features of NAFLD after Roux-en-Y gastric bypass surgery-induced weight loss, despite significant histopathology at baseline and substantial weight loss.

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