The Effect of Weight Loss and Weight Maintenance on High Density Lipoprotein Cholesterol and Selected Tissue Cholesterol Levels in Lean and Obese Zucker Rats

Abstract

Obese and lean Zucker rats were studied to compare the effects of a 6-week weight loss regimen (period 1) and a subsequent 4-week weight maintenance period (period 2) on high density lipoprotein (HDL2, d = 1.063-1.125 g/m.) cholesterol, plasma, adipose tissue, liver, and total body cholesterol. The effects of weight loss were compared with animals not subjected to weight reduction (control, period 0). Weight loss was achieved by reducing food intake below maintenance levels. Plasma cholesterol did not change significantly among the three periods in obese and lean rats. HDL2 cholesterol was higher (P < 0.05) in obese and lean rats at period 2 compared with the other periods. Adipose tissue cholesterol (per cell) did not differ among the three periods in obese and lean rats. Liver cholesterol (milligrams/gram liver) decreased significantly (P < 0.05) at period 1 and sustained this level at period 2 in lean rats, whereas liver cholesterol was unchanged among the three periods in obese rats. Carcass cholesterol (milligrams/gram carcass) in obese rats increased significantly (P < 0.05) after period 1 and sustained this level after period 2. Carcass cholesterol concentration was unchanged in lean rats. These data suggest that consideration must be given to homeostatic mechanisms of carcass and liver cholesterol concentrations in studies examining changes in plasma HDL2 cholesterol levels.