OBESITY AND DYSLIPIDEMIA - EPIDEMIOLOGY, PHYSIOLOGY, AND EFFECTS OF WEIGHT-LOSS

Obesity, an extremely prevalent health problem in our society, is associated with increased risk of atherosclerosis and its complications. When seen mostly in the abdominal region, obesity tends to associate with a lipoprotein pattern of elevated triglycerides, milder elevations of LDL-cholesterol, and lowered HDL-cholesterol levels. The mechanism by which this pattern occurs is complex, and likely involves increased fatty acid delivery to the liver, causing increased production of triglyceride rich lipoproteins. This greater utilization of fatty acid substrates and reduced utilization of carbohydrate substrates may produce a state of relative hyperglycemia and the resulting hyperinsulinemia may further contribute to hepatic triglyceride production. Increased lipolysis of triglyceride-rich particles is also seen in obese subjects, thus representing an overall increase in the metabolic activity of adipose tissue in obese subjects. Lowering of HDL cholesterol likely reflects the increased lipolysis of triglyceride-rich particles. Weight loss, if gradual and sustained, is associated with reversal of these lipoprotein abnormalities, independent of alterations in dietary fat intake. A combination of diet and exercise seems to have the greatest long-term benefit, with significant improvements seen even without normalization of weight.