How Much Do Genes Determine Health and Weight?

By Carol Crenna 

Do you think you’re stuck with what you got from your parents? You may feel that genes play a pretty big role in your health – you’re overweight because your parents are overweight, or it’s a roll of the dice whether you’ll get your mother’s breast cancer or your father’s hypertension. But that’s not the case.

Genetics only have a 20 to 25 percent influence on your life, according to Dr. John Diamond from Intemedica Clinic in Reno. It’s more the fact that you’ve inherited parents’ ways of thinking and of living which can amount to the same results.

Genes influence every part of your being. But there are two aspects: The genetic “type”– those genes given by parents, and the genetic “activity”, meaning which genes become active in your body, showing up and being expressed.

This means, for instance, if a high blood pressure gene inherited from your father is never given the right environment to become activated, you’ll never show signs or feel its ill effects throughout your lifetime even though have that gene. If the under-active thyroid gene from your mother is not called to express itself, then you won’t show symptoms such as lethargy and weight gain.

You are responsible for turning your genes “on” or “off”. If you live your life in a healthy way – fresh food, fresh air and exercise, and a fresh, positive outlook – you’re apt to express only your healthier genes. According to Dr. Mark Hyman (The Five Forces of Wellness), every single thing you do, eat, drink, feel and think causes different reactions in your genes that change from moment to moment in your body.

But Dr. Hyman says we’re like polar bears living in the desert, describing how our diet has changed from our ancestor’s, and our genes are suffering for it. He uses the plight of Arizona’s Pima Indians as an example. They thrived for thousands of years in the desert, eating very little, foraging for food in a scarce environment, with almost no disease. About 50 years ago they were introduced to white flour, white sugar and fat and their gene expression totally changed. They’re now the second most obese population in the world (second to Samoans), 30 percent suffering from diabetes, with a life expectancy of 46. Therefore, you are what you eat, but you’re also what you were born to eat.

Does your diet fit your genes?

According to an article in Time Magazine (June 2006), depending on your genes, certain foods are worse for some people than others. Nutrigenomics scientists say there are complex interactions between compounds found in your diet and your DNA. Jose Ordovas, a geneticist at the Friedman School of Nutrition at Tufts, states in the article, “We want to understand why nutrients do what they do and to whom–why a low-fat diet may not work for some but works for others.”

If you drink three cups of coffee a day, genetic tests can determine whether you, like 20 percent of the population, have a gene variation that makes it hard for you to absorb calcium if you drink caffeine. That can dramatically affect your teeth, muscles, and increase your bone loss. Are you getting enough B vitamins? Many people have a genetic predisposition that makes them absorb B vitamins poorly, putting stress on their nervous system, and in the case of folic acid, putting them at greater risk of heart disease. Is a high-fat diet worse for you than others, given your genetic makeup? About 15 percent are born with a liver enzyme that causes their HDL (good cholesterol) to go down when they eat fat.

Of the 25,000 genes of the human genome, tests have so far identified 19 that have a clear response to diet and lifestyle. They can test for calcium absorption, B vitamins, diabetes risk, Alzheimer’s risk, heart disease risk, insulin sensitivity, cholesterol levels and more. But they’ve just begun and comprehensive tests are still in the works. And since food also has hundreds of compounds with different reactions, it will take a while. In the end you’ll probably still need to eat your fruits and vegetables. But at least you’ll know which ones and why.