Question: I am a regular walker. Friends tell me I need to work up to jogging to really get a benefit from exercise. I don't like to jog. Does walking do me any good? I will look forward to your answer.

Answer: Actually, walking is a great activity for both fitness and health.

Your friends may be thinking that you are not working at a high enough intensity to get the full benefit in terms of causing physiologic changes in the aerobic system. It is quite clear that working at an intensity from around 70 percent to 85 percent of your maximum heart rate results in cir-cu-la-tory and muscle changes that cause a measurable increase in oxygen consumption. If you are fairly young and fit, walking may not stimulate the body to the point where these changes are made and therefore you may get health benefits but may not increase oxygen consumption as much as you would if you were working at a higher intensity.

A recent study reported upon in the New England Journal of Medicine followed more than 8,000 men of Japanese ancestry living in Hawaii. Researchers found that a daily stroll keeps older people living longer. For people in their 60s, 70s and 80s, walking can be powerful medicine. Over a 12-year period, this study found that covering just two miles a day cut the risk of death almost in half.

Other studies have related even job-related activity to longevity and decreased risk from death. Many years ago, Dr. Ralph Paf-fen-barger evaluated bus drivers vs. conductors in the double-decked buses of England. The conductors had only half the heart disease experienced by the drivers.

Later, postal workers and dock workers were compared to their less active bosses, with the same result. The bottom line is that any activity is better than none, and people who are active do decrease their risk of dying early. Unless you are interested in increasing your performance, walking is an excellent activity and will definitely affect your health in a positive way.

Question: What is the latest scoop on weight control? Have scientists found out yet why some people can't seem to lose weight?

Answer: There is a lot of research being done on obesity, especially in terms of genetics and messenger molecules. Several years ago a protein called leptin was discovered that, in animal studies, turned off the appetite.

When leptin was given to fat rats, they became thin. Just recently I read about another protein, orexin, a play on "orexis," the Greek word for hunger. The study that reported upon orexin suggested that the brain produces this chemical when it senses a need to eat, such as after a drop in sugar levels in the blood. Most scientists who work in this area believe there are many hormones that help us regulate our appetite and I am sure that science will develop a "cure" for obesity in the not too distant future.