Cholesterol levels in the U.S. continue to drop, in spite of two-thirds of Americans being overweight or obese. A recent report by the Centers for Disease Control and Prevention shows that only 13 percent of adults in the U.S. have high total cholesterol levels. Cholesterol is a waxy, fat-like substance found in the blood. The body needs cholesterol in limited amounts for proper functioning, but higher amounts can increase the risk of heart disease, the leading cause of death in the U.S. People with high total cholesterol are two times as likely to develop heart disease as those with optimal levels. High total cholesterol is defined as greater than 240 mg/dL, and optimal is below 200 mg/dL. From 2005 to 2008, the average cholesterol level for adults was 198 mg/dL, which is borderline high. The government had set a goal of no more than 17 percent of adults with high cholesterol. Men achieved this 10 years ago, and women five years ago. Weight is only one factor that affects cholesterol levels. Diet, exercise, age, gender, genetics and diseases like diabetes can all increase cholesterol beyond optimal amounts. Experts believe that cholesterol levels continue to drop, in spite of the obesity epidemic, because of a decrease in smoking and the wider use of cholesterol-lowering drugs. For most people, cholesterol levels are controllable with a combination of lifestyle changes and medications prescribed by a doctor. To get started, limit your intake of foods high in saturated fats and cholesterol, stop smoking and exercise at least moderately each day. To keep cholesterol in line, have your levels checked at least once every five years.