RELATIONSHIP BETWEEN OBESITY AND CONCENTRATION AND COMPOSITION OF LOW-DENSITY-LIPOPROTEIN SUBFRACTIONS IN NORMOINSULINEMIC MEN

Obesity, insulin resistance (IR) with hyperinsulinemia, and a dyslipop roteinemia characterized by reduced high-density lipoprotein 2 (HDL(2) ) cholesterol and elevated levels of small, dense low-density lipoprot ein (LDL) particles are risk factors for coronary artery disease (CAD) . The impact of obesity independent of hyperinsulinemia on the concent ration and composition of small, dense LDL subfractions is uncertain. The aim of this study was to investigate the relationship between obes ity indices, namely body mass index (BMI), skinfold measurements (SF), and waist to hip ratio (WHR), and LDL-subfraction particle concentrat ion and composition in 200 healthy men without evidence of IR. A preci se analysis of the concentration of lipids and apolipoproteins and the composition of very-low-density lipoprotein (VLDL), intermediate-dens ity lipoprotein (IDL), and two HDL- and six LDL-subfraction particles was obtained using the technique of density-gradient ultracentrifugati on. Dividing the individuals according to BMI showed that those with a BMI greater than 27 kg/m(2) had significantly lower HDL(2) cholestero l and apolipoprotein (ape) A-l and higher VLDL and IDL cholesterol and apo B concentrations than those with a BMI less than 25 kg/m(2). Rega rding LDL particles, we found that men with a BMI above 25 kg/m(2) had significantly more small, dense LDL particles (d 1.044 to 1.063 g/mL) and correspondingly fewer medium, dense LDL particles (d 1.031 to 1.0 37 g/mL) than leaner men; those with a BMI above 27 kg/m(2) had the hi ghest concentration of circulating small, dense LDL particles. These f indings were not influenced by fasting insulin concentrations, IR, or WHR. This study showed that obesity (BMI > 25 kg/m(2) associated with significantly higher SF, percent body fat, and waist circumference) is an important factor for the expression of a more atherogenic LDL-subc lass phenotype even in normoinsulinemia. Characteristic differences in composition of LDL-subfraction particles between lean and obese men u nderlie the role of body weight in the metabolism of LDL-subfraction p articles. Copyright (C) 1995 by W.B. Saunders Company