As a high school, college, master's and senior competitive runner, I used to often wonder why it was so difficult to lose extra weight as I grew older. Now I know why.

The scientific facts I am about to share with you are only intended for runners who are trying to shed extra pounds, and who are an O blood type. I know a lot about O positive blood types because I am one.

If your blood type is A, B or AB, then what I am sharing here may be the exact opposite for you, and therefore the knowledge I share should not be implemented by you unless you are an O positive or O negative blood type, and you have first consulted with your personal physician.

Believe it or not, your blood type is a more reliable measure of your identity than race, culture, or geography. It is a genetic blueprint for who you are, and a guide to how you can live most healthfully. Your blood type is older than your race and more fundamental than your ethnicity.

A single drop of blood, too small to see with the naked eye, contains the entire genetic code of a human being. The DNA blueprint is intact and replicated within us endlessly, through our blood. I was impressed to learn this fact.

More than 90% of all factors associated with your blood type are related to your primary type-O, A, B, or AB-and not whether you are positive or negative. Most of the distinctions between our blood types are found in our digestive and immune systems.

Like millions of Americans and especially those who pursue competitive running at any age, I have had trouble losing the "inner tube" around my waist.

Gaining excessive weight is a serious health risk, the details of which I do not need to mention here. Most overweight people know that the basic health risks are life threatening.

I am 5-foot-9 and my running weight in high school was 111 pounds and in college it was 118 pounds, the 7-pound weight gain was added muscle, not fat.

My weight a few months ago was 225 pounds with at least 65 pounds of that in my abdominal area, meaning a more reasonable weight for me at 63 years old would probably be 160 pounds.

That is where I am now headed since using science to develop a lifestyle plan that will shed my excess pounds in a prudent and healthy manner.

The reward for me personally is that not only will I become healthier and live longer, but I will become much more competitive as a middle distance runner in master's and senior competitions at both the local and national level.

Any serious runner knows that you cannot compete effectively if you are carrying an extra 50 pounds. It is like strapping a 50-pound bag of dog food onto your back and trying to run a race.

Runners know what I am talking about. There is a definite correlation between your weight and your cardiovascular efficiency; the less weight the better the cardiovascular efficiency.

When you have been to the top of the mountain (become a record-setting champion) you never forget, you want to remain on top, and no one ever-and I mean ever-can take away your feeling of winning and being a winner in life.

Becoming a winner again in competition offers me a lot more of an incentive to do what it takes to lose weight than just losing weight for health reasons, even though the latter can shorten my life.

Most of the competitions I have been in as a senior runner (50 and older) have found me unable to drop weight quickly and effectively without injuring my physical condition and general health.

That is why I feel so blessed to have read Dr. Peter J. D'Adamo's book Eat Right for Your Type which chronicles the four basic blood types, and why each thrives on a different diet, stress/exercise profile and personality type.

Dr. D'Adamo's clinical and laboratory results are facts based on science, not theory or speculation.

(Editor's Note: This is Part 1 of a 5-Part Article.)