Here's some good news in a sea of overwhelmingly bad information for American health: overall cholesterol has been steadily falling over the past 20 years, while good cholesterol has improved. The researchers' findings have buoyed doctors, but it is befuddling, considering the uptick in obesity during the same time period.

The study, published in the Journal of the American Medical Association, regarded the years between 1988 and 2000. The study found that the average overall cholesterol levels fell from 206 to 196 milligrams per deciliter of blood. The average "bad" cholesterol, or LDL, levels fell from 129 to 116, while the average "good" cholesterol, or HDL, rose from 50.7 to 52.5.

High levels of LDL, as well as low levels of HDL, can lead to numerous health problems, such as heart disease. The cholesterol levels mean that Americans have dipped even below the U.S. federal government's Healthy People 2010 goal, which set cholesterol goal levels at 200. That goal is in line with the American Heart Association's recommendation that healthy hearts have overall cholesterol levels of less than 200. The AHA also recommends that LDL is lower than 100 and that HDL is over 60.

While medical professionals are ecstatic about these findings, they do not have a clear idea of why these improvements have occurred. One solution may be the increase in the use of statins, which lower cholesterol. One statin drug called Lipitor, for example, is the best-selling medication of all time. Though statins are certainly a factor, people who were not taking the drugs also reported similar improvements in the study. Researchers credit healthier diets by people who are reducing their intake of trans fats and carbohydrates - aided, in part, by politicians. New York City, for example, banned trans fats in restaurants in 2007, a policy that has seemed to make New Yorkers healthier.

The news may seem at odds with other findings, namely that Americans are more obese and overweight than ever before. Indeed, the CDC reports that over one third of adult Americans are obese; Colorado, the state with the lowest percentage of obese adults, still reports that over 20 percent of adults in the state are obese. Advice by public health officials to increase physical activity has gone unheeded as well.

Nonetheless, while researchers have not pinpointed the reasons for the improvement, the news is still cause for celebration.