Abstract 1339: Correlates of Changes in HDL and LDL Particle Size in Response to a Physical Activity/Eating Lifestyle Modification Program in Viscerally Obese Men
Introduction: Endurance exercise training and weight loss have favourable effects on several features of the lipoprotein-lipid profile including HDL and LDL particle size. However, the correlates of changes in HDL and LDL size in response to a lifestyle modification program are not fully understood.
Objective: We examined the impact of a 1-year lifestyle modification program on HDL and LDL size measured by gradient gel electrophoresis and sought to identify which of the biological and anthropometric parameters are associated with these changes.
Methods: Visceral adiposity was assessed by computed tomography and a complete fasting plasma lipoprotein-lipid profile was obtained at baseline and after a 1-year lifestyle modification program in 109 abdominally obese men aged 30 to 65 years without diabetes.
Results: After 1 year, both HDL (81.7±2.1 vs. 83.9±3.1 Å, p<0.0001) and LDL (252.3±3.8 vs. 253.7 ±3.8 Å, p<0.0001) sizes were increased. Men were then stratified into 3 groups (≥50th percentile): men who did not increase HDL and LDL size, men who increased either HDL or LDL size and men who increased both HDL and LDL sizes. The latter group of men showed several significant changes in adiposity variables (especially visceral adipose tissue) including the most substantial changes in HDL-cholesterol and triglyceride levels compared to the two other groups. Multivariate analyses revealed that the best model predicting changes in LDL size in response to the lifestyle modification program was changes in HDL-cholesterol and in triglyceride levels, which explained 20% of the variance in LDL size changes (p=0.002). Changes in HDL size were not associated with changes in any variables of the lipoprotein-lipid profile nor with changes in adiposity variables.
Conclusion: These results indicate that, in abdominally obese men, a lifestyle modification program significantly increased HDL and LDL size. The increase in LDL size was partially explained by the increase in HDL-cholesterol and the reduction in triglycerides. Therefore, the increased LDL size resulting from a lifestyle modification program appears to be largely explained by the effects of such intervention on HDL-cholesterol and triglycerides.