Dr. Mark Hyman: Is Weight Gain Dictated by Genes?

“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

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.

Read page 1

Biochemical Individuality Underlies Everything

Rather than obsessively worry about genetics, your body becomes the best way to gauge how you should eat. How do you feel after eating certain foods? Are you feeling alert and vibrant with abundant energy, or are you feeling sluggish, bloated and foggy?

Most people do much better with a higher-fat, lower-carbohydrate diet. Research supports this. A one-year, multi-center controlled trial, published in The New England Journal of Medicine, looked at 63 obese men and women randomly assigned to either a low-carbohydrate, high-protein, high-fat diet or a low-calorie, high-carbohydrate, low-fat conventional diet. The low-carbohydrate diet participants lost more weight and had lower levels of triglycerides, cholesterol, blood pressure and blood sugar levels.

Yet this wasn’t the case for everyone. We are all unique individuals with different biochemical needs. We all do better with fewer refined carbohydrates which break down into sugar. More sugar means more insulin, which means more inflammation. That’s never a good situation.

Some people do better with more carbohydrates or less fat. Again, your body will let you know—just focus on how you feel and what works best for you.

A scale and your lab tests can also help you determine what works best. Let’s say you have developed type 2 diabetes, which you desperately want to reverse. You may need a high (up to 60 to 70 percent) amount of healthy fats and a low (five to 10 percent) amount of carbohydrates. This may seem extreme. But it sometimes takes extreme change to get extreme results, especially when you’re trying to reverse disease.

Interestingly, once you heal your body and reverse diabesity, you may be able to handle more varieties of foods as your body becomes more resilient.

My point is that works for others might not work for you. Everyone is different and has different biochemical needs. And yes, some people have genes predetermined for obesity, type 2 diabetes and other complications. Even so, you’re not doomed.

7 Ways to Simplify Weight Loss

While your genes play some role, they do not determine your destiny. Regardless of your genetics and other conditions, everyone can start with these seven strategies for weight loss and optimal health:

1. Focus on eating real, whole foods. Eat plenty of non-starchy vegetables, some lower-sugar fruits if you can tolerate them, grass-fed meats, pastured chicken and eggs and wild-caught fish.

2. Eat plenty of healthy fats like avocados, coconut oil, nuts and seeds, extra-virgin olive oil and some grass-fed butter. Eating healthy fats helps burn fat by speeding up your metabolism. Your cells and brain also require fat to function at optimally.

3. Avoid processed sugars and refined carbohydrates. Limit your grain intake from breads, cereals, pastas, rice and starches. Avoid baked goods and sweets and watch your intake of alcohol.

4. Take optimal nutrients. A good multivitamin and multimineral covers the nutrients that you’re probably not getting from food. I also recommend a professional-quality fish oil, extra vitamin D and magnesium, a probiotic and a fiber supplement to help balance blood sugar levels. You can find all these and other quality supplements in my store

5. Control stress levelsBeing constantly stressed out wreaks havoc on your health, hormones and weight. Find something that helps you tamp down stress, whether it’s yoga, meditation or deep breathing. Many patients find my UltraCalm CD helps dial down stress levels. 

6. Get adequate sleep. Sleep deprivation makes you fat and can also contribute to depression, pain and inflammation, heart disease, diabetes and many other health issues. Getting at least seven to eight hours of sleep is vital to optimal health. Avoid exposure to artificial light from smart phones, television and other electronics too close to bedtime. Read 19 of my top sleep tips here.

7. Exercise regularly. Get on a regular routine of exercise and move your body. You can’t exercise your way out of a bad diet, but exercise does make your cells and muscles more sensitive to insulin so you don’t need as much. Less insulin means less inflammation and less body fat, especially dangerous belly fat. If all you are able to do is walk that is fine. You’ll want to do a minimum of 30 minutes of walking daily. Others may be able to handle more advanced exercise. Studies demonstrate the benefits of high intensity interval training (HIIT), which you can do in as little as 20 minutes. It’s much more effective than longer durations of low-intensity cardio workouts.

In a nutshell: Stop worrying about your genes! You can do plenty to ensure you are on the right path to achieving healthy weight and optimal health. Your lifestyle and food choices are much better indicators of your health and weight than your genes.

You can create optimal weight and metabolism and reverse most chronic disease. Some of us have to work a bit harder and for some it is much easier, but it’s very possible for almost everyone. Never, ever lose hope.

To learn more about the healthy fats I mentioned here and how they can help you become lean and healthy, look for my new book Eat Fat, Get Thin.


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