Plasma lipoproteins and lipase and lecithin:cholesterol acyltransferase activities in obese subjects before and after weight reduction.

Plasma lipoprotein concentrations and post-heparin lipoprotein lipase, hepatic triglyceride lipase (HTGL), and lecithin:cholesterol acyltransferase (LCAT) activities were determined in 10 obese women before and after weight loss. In period I, a diet was given to maintain constant weight for 3 weeks. In period II, total calories were restricted to 600 kilocalories/day for 3 weeks. In period III, caloric intake was adjusted to maintain weight at the lower level for 6 weeks. The lower calorie diet decreased plasma very low density, low density, and high density lipoprotein (HDL), cholesterol, and apolipoprotein B and A-I concentrations and molar enzyme activities, while the percent conversion of free to esterified cholesterol by the LCAT enzyme was unchanged. During weight stabilization at a lower state (period III), the mean plasma HDL cholesterol level increased, and lipoprotein lipase and LCAT activities increased to values higher than those in period I. The mean HTGL activity remained reduced. I conclude that successful weight loss improves the possibly atherogenic plasma lipoprotein profile of obese subjects. The increase in HDL cholesterol and cholesterol esterification, possibly explained by lowered HTGL enzyme activity, may increase the capacity of HDL to transport cholesterol from peripheral cells to the liver.