Effect on Hepatic Morphology of Treatment of Obesity by Fasting, Reducing Diets and Small-Bowel Bypass

TLDR

Liver biopsies of 41 obese subjects undergoing >100 lb weight loss were performed across three treatment groups: prolonged fasting, low‑calorie dieting, and intestinal bypass surgery. While fasting and dieting caused only transient hepatocellular degeneration that resolved to normal histology, bypass surgery led to progressive fatty changes, cholestasis, inflammation, fibrosis, bile‑duct proliferation, and fatal necrosis, with morphologic damage occurring despite normal liver‑function tests, indicating that follow‑up biopsies are essential to assess bypass‑related hepatic injury.

Abstract

Liver biopsies in 41 grossly obese subjects were evaluated during massive weight reduction (more than 100 lb). The subjects comprised three groups who had been treated by prolonged fasting, low-calorie dieting and intestinal bypass surgery. The first two groups manifested a transient increase in the degree of hepatocellular degeneration and focal necrosis along with progressive diminution of fatty infiltration during acute weight loss. Late follow-up biopsies revealed histologically normal livers. In contrast, bypass surgery was followed, variously, by massive fatty changes, cholestasis, polynuclear inflammatory infiltrates, diffuse fibrosis, bile-duct proliferation and fatal hepatic necrosis. Morphologic changes occurred while liver-function tests were still within normal limits. Follow-up biopsy examinations are the only reliable means of judging whether a bypass procedure is causing progressive parenchymal damage.