We’re all dealt a genetic hand at birth – the traits handed down to us from our parents. You might be pleased as punch that you inherited your aunt’s cheekbones and dimples or your mom’s intelligence, but other traits, like a tendency to put on body fat, might be less desirable.
A significant portion of the population harbors a gene called the FTO gene that places them at higher risk for obesity. People in all cultures around the world carry this gene, although it’s most common in Europeans and least common in East Asians and Africans. As many as 43% of Europeans have this gene that slows the metabolic rate and makes it easier to put on body fat.
What’s exciting is exercise appears to blunt the effect of this common “fat storage” gene. When researchers analyzed data from 17,400 people from all over the world and the impact of lifestyle factors on obesity genes, they discovered exercise is key to reducing expression of the FTO gene. In fact, moderate exercise blunts expression of this gene by as much as 75%.
More good news. The quantity of exercise required to weaken the expression of the gene is modest. In fact, exercising as little as a few hours a week helps prevent weight gain in people with this gene. No more using “bad genes” as an excuse!
Why is the “obesity gene” so common? One theory is called the “thrifty gene” hypothesis. According to this theory, having genes that promote fat storage and conservation of energy protects against starvation during times of famine. That’s important for survival in certain environments, but most of us live in an environment where there’s TOO much food available and portion sizes are too high. Obesity genes no longer provide benefits. In fact, they work against us.
Is Obesity an Inherited Disease?
No doubt, there is a genetic component to obesity. In fact, the risk of becoming obese is up to 8 times greater for an individual who has a strong family history of obesity. The genetics of obesity is more complicated than simply carrying a single gene, the FTO gene. Although being a carrier of this gene DOES increase the risk for obesity, a number of different genes, as many as 56 according to one study, impact an individual’s chance of becoming obese.
Plus, it should come as no surprise that you can be overweight or obese without inheriting ANY of the common genes linked with obesity. The body weight you achieve involves an interplay between genetics and the environment, and as the FTO study shows you can overcome bad genetics with lifestyle, in this case, exercise. In addition, we now know the environment can affect the expression of genes, a process called epigenetics. Just because you inherit a genetic predisposition to be obese or another health problem doesn’t mean you’ll develop that condition. What you eat, your activity level, and what you’re exposed to in your everyday life impacts the expression of the genes you inherit.
Environmental Factors
Some experts are skeptical that the rising rate of obesity can be blamed on genetics. They claim that the gene pool couldn’t have changed quickly enough to explain why people are becoming obese at such a fast rate. Instead, they point to what HAS changed in the past fifty years – portion sizes have become larger, people consume more fast food, and activity rates have dropped. Plus, we’re exposed to more toxins that may be “obesogenic,” like those we breathe in and BPA in plastic food containers etc. All in all, the environment has changed. Combine that with a genetic susceptibility, like carrying the FTO gene, and your likelihood of becoming overweight or obese goes up.
Although exercise helps blunt the impact of the FTO gene, even if working out doesn’t lead to weight loss, it STILL has benefits. According to a study published in the Journal of Clinical Endocrinology and Metabolism, the health benefits of exercise accrue in the absence of significant weight loss. In this study, researchers followed 866 middle-aged women for almost 7 years.
In this study, obese women who exercised regularly had a lower risk for developing health problems related to obesity such as metabolic syndrome and heart disease even if they didn’t lose weight. That’s encouraging! Even if you never get down to your ideal body weight, you’ll still lower your risk for health problems and premature death if you work out.
Keep Your Workouts Balanced
If becoming more metabolically healthy is your goal, it would be shortsighted to do only aerobic exercise, as some people do. Resistance treating is equally important, if not more so, for metabolic health. Resistance training improves insulin sensitivity, and the more muscle you carry on your body, the better your body handles glucose. A number of studies show that having more lean body mass reduces risk factors for metabolic syndrome and type 2 diabetes.
Plus, not weight training to preserve lean body mass can lead to another form of obesity – normal-weight obesity – where your weight is normal but your body fat percentage is too high due to loss of muscle tissue. In addition, resistance training and building muscle modestly increase your resting metabolic rate. All of these things together help you better control your weight and reduce your risk for health problems like type 2 diabetes and heart disease. Muscle rules – especially as you age.
The Bottom Line
Regardless of the genetics, your parents handed down to you, you have a powerful weapon in the fight against obesity – exercise. Aerobic exercise is important, but don’t underestimate how critical resistance training is for helping you avoid fat gain and the problems that come with it – metabolic syndrome, heart disease, and type 2 diabetes. No matter what your genetics or how much you weigh, it’s important to stay active.
References:
Trends Genet. 2010 Jun; 26(6): 266-274. doi: 10.1016/j.tig.2010.02.006.
Research Chair in Obesity. “Genetic factors of overweight and obesity”
Centers for Disease Control and Prevention. “Behavior, environment, and genetic factors all have a role in causing people to be overweight and obese”
Medical News Today. “Women can maintain metabolically healthy obesity through exercise”
Journal of Obesity. Volume 2011 (2011), Article ID 482564, 9 pages.
Circulation. 2007 Jul 31;116(5):572-84. Epub 2007 Jul 16.
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