One of the most shocking surprises to emerge from the Human Genome Project in 2003 is the discovery that we are the proud owners of a paltry 30,000 genes — barely twice the number of a fruit fly.

After a decade of hype surrounding the project that gave us the full sequence of our human genome, and the regular discovery of genes for killer diseases and complex traits, this unexpected result led many scientists to a stunning conclusion. The seesaw struggle between our genes (nature) and the environment (nurture) had swung sharply in favor of nurture. “We simply do not have enough genes for this idea of biological determinism to be right,” asserted Craig Venter, president of Celera Genomics, one of the two teams that cracked the human genome.

 Although some diseases are inherited through a single genetic mutation — cystic fibrosis and sickle cell anemia are examples — the classic “one gene, one disease” model doesn’t adequately explain the complex interplay between an individual’s unique genetic code and his or her personal history of environmental exposures.  Think of genetics as the “loaded gun” and your environment as “pulling the trigger.”  That is, if an individual with a predisposition to develop diabetes were put in an environment where they gained excess weight, they would likely become diabetic.  Conversely, if that same individual were put in a different environment where weight gain was difficult, they would be less likely to develop diabetes. 

Why is this important?  Obesity, or excess body fat, has been associated with a number of chronic diseases, including an increased risk of heart disease, high blood pressure, stroke, arthritis, depression and seven different cancers.  But of all the diseases associated with obesity, there is no stronger association than the one it has with diabetes.

 Over the last 20 years, there has been a frightening increase in the number of Americans that are obese or overweight.  The National Health and Nutrition Examination Survey has tracked the rise in obese and overweight adults since 1999.   Using Body Mass Index (BMI) data, the survey found that 32% of men and 35% of women were classified as obese, which meant their BMI exceeded 30.  This may be a conservative estimate, since BMI is an inexact measure and may actually underestimate the number of people at risk for adverse health outcomes such as cardiovascular disease, diabetes metabolic syndrome and certain cancers.  Some studies suggest that half of the people with a normal BMI (less than 25) may have an elevated body fat percentage.  Confirming this trend is a recent study by the Centers for Disease Control that estimated the body fat percentage of a typical American woman to be 40% and the typical American man at 28% based on a six year analysis of data.  These body fat measurements are nearly twice as high as what are considered ideal. 

 During that same time period, medical professionals have witnessed an alarming increase in the number of individuals diagnosed with type 2 diabetes.  During these past two decades, diabetes-related deaths climbed by 45% in contrast to declining death rates for cardiovascular disease and cancer.  An estimated 57 million Americans are at risk for diabetes, with another 24 million adults and children already diagnosed with the disease.

 Even as science searches for more clues about the causes of diabetes and medications to prevent it, the vast majority of new cases of the disease in older adults could be prevented by following a modestly healthier lifestyle, according to research led by scientists at the Harvard School of Public Health.  Their findings support the theory that diabetes really is a lifestyle disease. It is largely preventable by modifying five lifestyle factors:  physical activity, diet, smoking habits, alcohol use, and amount of body fat.  Although this study was conducted on adults over age 65, several studies have similarly linked these factors with diabetes risk on an individual basis.

 Two-thirds of diabetics will die prematurely from heart disease or stroke.  Nearly 70% of them will suffer nerve damage that can lead to pain and tingling in the hands and feet, sexual dysfunction, and digestive problems.  Diabetics are ten times more likely to have an amputation and diabetes is the leading cause of blindness and kidney failure.

What can be done about it?  We are not slaves to our genes; just because the gun may be loaded, the trigger never has to be pulled.  Adopting a healthier lifestyle could prevent the majority of type 2 diabetes cases.  It isn’t pure coincidence that the same healthy lifestyle modifications could prevent more than 80% of cardiovascular disease cases and virtually curtail the obesity epidemic.  It is a commitment and a forward-looking approach to living.  How you choose to live now will directly impact how you feel and function in the decades to come.  Start living better.