06/26/2013 09:43 am ET Updated Aug 26, 2013

Can You Turn Off Your Fat Genes?

Have you ever wondered why some people seem to do very well on a diet and exercise plan, while others seem to fail with the same plan? Much of this is due to the fact that everyone has a unique body type that will respond differently to a specific workout or nutrition plan. This is a concept known as "somatotyping." I discuss it more comprehensively in my book Get-Fit Guy's Guide to Achieving Your Ideal Body.

But earlier this month, an interesting study was released suggesting that the way your genes express themselves can predict which specific diet or exercise regimen may work best for your body. This means that at some point in the future, a simple salivary test may be able to tell you what kind of fat loss or muscle gain program is going to work best for you.

So as genetic fitness and diet customization becomes a reality, what about the opposite end of the spectrum? Can your genes make you fat? Is there such a thing as a fat gene or a genetic propensity for obesity?

Is There a Fat Gene?

Studies for the past decade have demonstrably proven a link between genetics and propensity for being overweight or obese. For example, in a UCLA study, researchers gave more than 100 genetic variations of mice a normal diet for eight weeks, followed by a high-fat, high-sugar diet (aka, the SAD "Standard American Diet") for another eight weeks.

Even though all the mice were eating the identical diet, their weight gain varied significantly. The calorie-laden diet caused absolutely no body fat change for some mice while other mice eating the identical diet experienced a body fat increase of more than 600 percent!

The researchers were able to attribute this largely to genetics and were able to identify and compare 11 separate genetic regions that were associated with the fat gain in the group of mice that had a more deleterious response to the diet. You could of course argue that mice are very different from people, but several of these genes did indeed directly overlap with genes linked to obesity in humans.

One of the study authors said that he hopes this research will lead to new drugs and treatments that specifically target or "turn off" the fat genes. But a more important note on the study was the emphasis that no matter what the genes say, environmental factors such as diet and exercise are also extremely important when it comes to whether or not your genes are going to make you fat.

And that's exactly what is most important here, since it has been proven quite clearly in another study that physical activity can reduce your genetic tendency toward obesity by up to 40 percent!

How to Combat Your Fat Genes

Here's the good news: You can get the benefits of exercise without running marathons, doing triathlons, or spending every waking hour in the gym. In fact, being active for about 30 minutes a day is all it takes to directly minimize the effects of "fat genes." This means that you can counteract the effects of your fat genes by engaging in non-structured exercise such as simply walking the dog every morning, taking your bike to work, skipping the elevator and walking the stairs instead, or even taking cold showers.

But physical activity isn't the only way to reduce the effects of your fat genes. You can also make a difference with your lifestyle, your diet, and even your emotional state (which directly affects stress and cortisol levels). As a matter of fact, you are constantly changing your genetics or pulling specific genetic triggers on a daily basis, and even hourly, with the type of foods you eat, the quality of the air you breathe, the physical activity you do (or don't do), and even by the amount of stress in your life. An entire field of study called epigenetics is devoted to this dynamic changing and on-off switching of genes.

For example, not getting enough nutrients from your diet, or cigarette smoking, or long term exposure to toxins and pollutants can affect not only your own gene expression, but also the health, propensity for disease, weight, and life of your children, your grandchildren, and the multiple generations that come after you.

So the good news is that you can not only stop your own fat genes, but you can make the right decision for future generations. If you need help getting started with the bare minimum, you can read or listen to "What's the Minimum Amount of Exercise You Can Do?" and check out to learn more about how to customize workouts for your unique body type (which is of course based on your genetics).

Ben Greenfield is a fitness and triathlon expert and host of the Get-Fit Guy podcast on the Quick and Dirty Tips network. His latest book is Get-Fit Guy's Guide to Achieving Your Ideal Body: A Workout Plan for Your Unique Shape.

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