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mhymanbw“For generations, my family has been overweight or obese and I’m just wondering how much of weight gain is dictated by genes?” writes this week’s house call. “Do my genes create my destiny?”

Let’s get the bad news out of the way first. Some genes can predispose you to obesity, type 2 diabetes or heart disease. But predisposition is not pre-destiny. Ninety percent of our current health is controlled by the environment in which we bathe our genes—the food we eat, our exercise regimen, our resilience in the face of stress and our exposure to environmental toxins.

In other words, a familial history of obesity or chronic disease does not render you powerless. You don’t have to sit back and accept that you’re doomed to become fat and sick.

Photo credit: iStock
Photo credit: iStock

In a comprehensive study on genes and obesity, researchers identified 32 different genes that can contribute to obesity. Even in the unlikely case you actually had all 32 genes, they would only account for 22 pounds of extra weight.

Some people (in fact most people—about 70 percent or so) are more likely to be carbohydrate intolerant and insulin resistant setting the stage for overweight or obesity. And some ethnic groups are at much higher risk—including those of Asian, East Indian, Native American, Pacific Islander or Middle Eastern descent. And of course, if you have a family history of type 2 diabetes, you are predisposed to become diabetic.

For these folks, a little bit of sugar or starch makes their bodies create much more insulin than the average person. This vicious cycle triggers weight gain, hunger and fatigue, as well as high blood pressure, obesity and type 2 diabetes.

Yet even with all these factors, you’re not doomed. We don’t have to accept that familial disposition to certain conditions means developing them is inevitable. By eating well and exercising, you can completely prevent obesity or type 2 diabetes, what I collectively call diabesity.

Genetics Loads the Gun, but Environment Pulls the Trigger

While genetics certainly impacts weight gain, environment plays a far bigger role, as the Pima Indians of Arizona show.

The Pima Indians had a metabolism exquisitely adapted to their environment. They had evolved to thrive perfectly on particular foods that exist only in a desert environment. One hundred years ago they were thin and fit with none of the diseases of Western civilization, such as obesity, heart disease and diabetes.

Yet in a single generation, they became one of the most obese populations in the world, second only to the Samoans. Eighty percent of them develop type 2 diabetes by the time they reach 30 and their life expectancy is only 46 years.

Did they suddenly mutate and get the obesity gene? No. The answer is much more complicated than that. Traditionally the Pima diet consisted of whole grains, squash, melons, legumes, beans and chilies supplemented by gathered foods including mesquite, acorns, cacti, chia, herbs and fish. Their diet included whole, unrefined and unprocessed foods, which (technically) is a high-carbohydrate diet, albeit a healthy one. Remember, all veggies are carbs—just the health, unrefined kind.

The Pima Indians were a fit and healthy people until their diet changed. Over the course of one generation, they went from eating this traditional diet to eating the traditional American diet featuring high-sugar, high-flour, high-processed food, which is a very different kind of high-carbohydrate diet.

At the same time, their cousins in Mexico are thin and healthy because they’ve maintained their traditional diet and lifestyle.

The Genetic Connection to Weight Gain

As the Pima Indians show, environment definitely plays a role in fat loss, but so do genes, to some degree. The Pima Indians have what we call the thrifty gene hypothesis: Some people are well designed to store excess food when it is available, setting the stage for diabesity.

Other genes also contribute, such as brain genes, which code for receptors for the pleasure-producing neurotransmitter dopamine. In some cases, these genes make dopamine receptors that are not as responsive to dopamine’s pleasure signals and that makes us eat more and more in order to be satisfied.

When I mention drugs, you probably think cocaine or heroin. Indeed, they trigger dopamine receptors. Yet refined carbohydrates and sugar, the most abundant abused drug, also trigger these dopamine receptors. When your dopamine receptors need more stimulation to feel pleasure, they set the stage for cravings and addiction.

We are very aware that sugar acts just like cocaine and drives food addiction, as well as overeating. I described the science of this in great detail in The Blood Sugar Solution 10-Day Detox Diet and provided a clear plan to break the sugar and refined carbohydrate addiction.

Research shows sugar is actually much more addictive than cocaine. In one study, researchers offered rats sugar or cocaine. No contest: The rats chose the sugar over the cocaine.

Researchers concluded extreme stimulation of the brain’s pleasure receptors by sugar-rich diets generates an extreme reward signal in the brain, overriding the self-control mechanisms and leading to addiction.

Other genetic factors also play a role here. New and emerging research shows how different people have varying responses to carbohydrates and fats. Some of us do better with more omega 3 fat, while others thrive on saturated fatSome people do better with more omega 6 fats. There can be a big difference in how we respond to different types of fat. Those effects impact blood sugar, cholesterol and even gut bacteria.

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