Effects of weight reduction on plasma lipoproteins and adipose tissue metabolism in obese subjects

Abstract

The relationship between obestity and alterations in adipose tissue metabolism and lipid transport was studied in 14 obese human subjects before and after a weight reduction of 4-22 kg. Blood glucose and plasma insulin patterns after oral glucose intake improved significantly, and plasma glucagon levels decreased markedly after treatment. Plasma triglyceride and total cholesterol levels were not altered, but there was a 20% (P < 0.05) increase in HDL (high density lipoprotein) concentrations. Plasma free fatty acid and glycerol concentrations decreased, in parallel to a decrease in lipolysis rate in vitro. Lipoprotein lipase and hepatic lipase activities in postheparin plasma, as well as the i.v. fat tolerance test, were normal and did not change significantly after weight loss. Lipoprotein lipase (LPL) activity in adipose tissue, expressed per cell, was elevated and did not change after weight reduction. Also, the enzyme activity did not increase after glucose intake before or after treatment. The lack of effect on LPL activity and regulation in combination with significant improvements of other aspects of lipid and glucose transport is consistent with the view that alterations in LPL activity and regulation may represent an early and possibly primary defect in the development of obesity.