MANILA, PHILIPPINES: I am a married Asian male who used to smoke, drink and do drugs in a major way. At 42 I have overcome these habits, although I drink occasionally. Will my past behavior affect how I age?

It is never too late in one's life to make healthier lifestyle choices. The health risks of tobacco, over-use of alcohol and illicit drug use begin to decline within days after you stop them. How any or all of your past use will affect how long you live is very difficult to predict. Much of it depends on genetics that we are just beginning to understand. If there is no current evidence that alcohol or drugs damaged your liver or other organs, then it is unlikely you will have problems in the future. Cigarette smoking is not so straightforward. Quitting smoking can reduce your risk of heart disease back to baseline after five years. Although the risks of chronic lung disease and smoking-related cancers, especially lung cancer, go down after one quits smoking, the increased risk never goes away if a person has smoked regularly for many years.

EMMETT, MICH.: I hear so much about "deep-belly fat" and how it can kill you. This concerns me, because I have a large belly that I cannot lose. Dieting and exercise (including sit-ups) just don't get at it. I'm 50 and want to have a high quality of life for 30 more years or longer. What must I do to achieve this?

Visceral or deep-belly fat refers to the fat inside the abdomen that surrounds our internal organs, as opposed to the fat underneath our skin. The amount of visceral fat correlates somewhat better to waist size than to body weight. Don't be discouraged if you are not yet seeing the results from diet and exercise; what you see in the mirror may not reflect the health benefits from cutting calories and being physically active every day. More specifically, eat plenty of fish and avoid saturated fats. Use modest amounts of polyunsaturated fats such as canola and sunflower oil instead. Most important of all, step up the intensity of your exercise to a more vigorous level--once you have cleared it with your doctor.

SICKLERVILLE, N.J.: I'm 50 years old and worry about heart disease. (My dad and four of his brothers all had bypass surgery.) I exercise four days a week, take Lipitor daily and have my cholesterol checked every six months. My only vices are having a few drinks on weekends along with a few cigars. Other than diet, what else can I do?

You describe a healthy routine that has already modified your genetic risk of atherosclerosis and acknowledged the importance of diet. To lower your risk even more, maintain a body-mass index (BMI) of less than 25 to keep blood sugar, insulin levels and blood pressure down, even if all these are already in the normal range. Increase your exercise frequency to every day and go at a moderate intensity for 30 to 60 minutes. A little alcohol is good: an average of a couple of drinks per day for men and one per day for women. You should ideally stop the cigars. Keep taking the Lipitor and consider a higher dose if your LDL is greater than 100. In addition, a daily baby aspirin decreases heart-attack risk. Another consideration is getting your blood-homocysteine level checked. If the level is elevated, many doctors, including me, would recommend lowering it by taking folic acid, vitamin B12 and vitamin B6 (pyridoxine).

ALOHA, ORE.: Could a blood transfusion cause elevated cholesterol and glucose levels? My 55-year-old wife had very low levels of both before knee-replacement surgery. But when tested recently, she had borderline high levels of both.

If a blood test is drawn immediately after any type of intravenous infusion, such as a blood transfusion, the result might be spurious. However, there are no long-lasting consequences. Assuming that both the before and after blood samples were drawn in the fasting state, I suspect that the rise in blood sugar and total cholesterol levels is a result of her inability to be as active as she was prior to surgery. If she has gained weight during this time, as little as 10 extra pounds could significantly elevate her blood-glucose level. With inactivity and weight gain, some people will show a marked increase in the triglyceride fraction of total cholesterol.

AUSTIN, TEXAS: After I turned 40, I received a letter from a local doctor suggesting that I start receiving a monthly injection of HGH (human growth hormone) as part of an aggressive anti-aging strategy. Have there been long-term studies of the health effects of HGH on healthy older individuals? Are HGH injections really accepted practice by the medical community?

Although there is evidence that growth-hormone injections can increase muscle mass and physical performance and endurance in adults, this is not an approved use of the drug. The only FDA-approved uses of HGH are to treat children with short stature, adults with proven growth-hormone deficiency and people with weight loss and diminished strength related to HIV infection. The long-term effectiveness and safety of supplemental HGH in otherwise healthy people are unknown. Side effects of excessive amounts of growth hormone are similar to the manifestations of a rare disease called acromegaly--an unregulated excretion of growth hormone by a tumor in the pituitary gland. Manifestations include swelling of the ankles and feet, joint pain, elevated blood sugar and high blood pressure. Theoretically, HGH could also increase the risk of some cancers.