Effect of weight loss on LDL and HDL kinetics in the metabolic syndrome: Associations with changes in plasma retinol-binding protein-4 and adiponectin levels

Abstract

Objectives: To examine the effect of weight loss on LDL and HDL kinetics and plasma retinol-binding protein-4 (RBP-4) and adiponectin levels in men with the metabolic syndrome (MetS).

Research design and Methods: LDL-apoB-100 and HDL-apoA-I kinetics were studied in 35 obese men with the MetS at the start and end of a 16-week intervention trial of a hypocaloric, low-fat diet (n=20) versus a weight maintenance diet (n=15), using a stable isotope technique and multi-compartmental modelling.

Results: The low-fat diet achieved significant reduction (P<0.01) in BMI, abdominal fat compartments and HOMA score compared with weight maintenance. This was associated with a significant increase in adiponectin and a fall in plasma RBP-4, triglycerides, LDL-cholesterol, and LDL-apoB concentration (P<0.05). Weight loss significantly increased the catabolism of LDL-apoB (+27%, P<0.05), but did not affect production; it also decreased both the catabolic (-13%) and production (-13%) rates of HDL-apoA-I (P<0.05), thereby not altering plasma HDL-apoA-I or HDL-cholesterol concentrations. VLDL-apoB production fell significantly with weight loss (P<0.05). The increase in LDL catabolism was inversely correlated with the fall in RBP-4 (r=-0.54, P<0.05), and the decrease in HDL catabolism with the rise in adiponectin (r= -0.56, P<0.01).

Conclusion: In obese men with MetS, weight loss with a low-fat diet decreases plasma LDL-apoB concentration by increasing the catabolism of LDL-apoB; weight loss also delays the catabolism of HDL-apoA-I with a concomitant reduction in the secretion of HDL-apoA-I. These effects of weight loss could partly involve changes in RBP-4 and adiponectin levels.