Dietary Fat and High-Density Lipoprotein (HDL) Metabolism-Effect of Carbohydrate and Fat Intake

Generally, people with low levels of high-density lipoprotein (HDL) in blood are more likely to get heart disease than those who have normal or high levels. Dietary fat, whether the harmful type (saturated) or beneficial type (unsaturated) raises HDL levels. Dietary carbohydrate lowers HDL. The investigators are doing this research study to find out why the amount of HDL in a person's blood is affected by dietary unsaturated fat and carbohydrate. The investigators will trace the ability of the HDL in a person's blood to take up cholesterol, get bigger, and then leave the blood by passing into the liver. The investigators want to know if dietary unsaturated fat improves the ability of HDL to do this compared to dietary carbohydrate.