Why is one form of cholesterol considered good and another bad? There are actually as many as 18 kinds of cholesterol, but to save confusion, doctors divide them into two categories: LDL (bad) and HDL (good). Your liver manufactures most of your cholesterol, and small amounts of it go toward a variety of healthy purposes, including creating hormones that help turn food and exercise into muscle. Serving as cholesterol chauffeurs are fat/protein bunches called lipoproteins, and that's where the fun begins: Low-density lipoproteins tend to deposit cholesterol on artery walls, where it builds up and eventually interferes with blood flow. But the high-density variety seems to take cholesterol back to the liver, where it can be eliminated from the body.
As a result of all this, doctors don't just want you to lower your total cholesterol count; they want you to change the ratio as well, so you have more HDL and less LDL. "When we looked at the data, we found that the higher your HDL went, the lower your risk of heart attack," says cardiologist William Castelli, M.D., former director of the Framingham Heart Study in Massachusetts. An HDL level of 75 or more seems to convey extra longevity for many people, while a count of 100 or more is so beneficial that it was dubbed the "Methuselah syndrome" by one researcher. HDL less than 35 or so, meanwhile, can carry significant risk of heart disease. Genetics plays a large role in HDL. A few guys have naturally low levels and need to keep their LDL low as well to make up for it. (As Castelli puts it, you don't need a substance that removes cholesterol from your blood if you don't have much to begin with.) But there's plenty that everyone else can do to pump up their HDL. Never one to shirk from a task that doesn't involve housecleaning, I managed to find two handfuls of ways to turn my "good" numbers into great numbers.
Plain and simple, exercise raises HDL levels. "We looked at doctors and others who ran the Boston Marathon," notes Castelli. "While the average male HDL is 45, men who ran the marathon ranged around 55." One Georgetown University study found increased HDL in those who ran seven miles a week or took part in four moderate 30-minute sessions of any aerobic activity.