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On a typical night last fall, when I was sitting on the couch with my husband, watching bad TV and drinking a glass of red wine, I did something unexpected. Rather than scour the web for random fun tidbits and catch up on my Instagram feed, as I'd usually do, I registered to run my second marathon.
As a former track & field athlete who could once clock a 5:00 mile, I have a long history with running. But in recent years, I've had three kids and gradually grown out of shape and become a bit overweight. I'd wanted to improve my health for a while, so when I saw that a LA Marathon training program started the next week, it felt like kismet.
In the months that followed, I went from taking the occasional jog around my neighborhood to logging about 30 miles a week. But despite these efforts, my weight didn't budge. Although this is a well-known phenomenon for marathoners, I'd also started lifting weights once a week, cut down on alcohol and upped my veggie intake. Frustrated, I figured there had to be a more scientific way of getting the results I wanted, and in November, sent a small vial of saliva to a new, UK-based DNA testing company called FitnessGenes.
While most people have heard of 23andMe, the direct-to-consumer genetic testing company that's provided more than one million users with personalized information about their ancestry and genes linked to cystic fibrosis, Tay-Sachs and other diseases, there's also a more niche group of DNA tests designed to provide users with genetic findings related to their health and fitness. Companies in this emerging field, including FitnessGenes, DNAFit and Nutrigenomix, gather information on genes that affect muscle mass, endurance, fat burning ability and metabolism, among other traits, and often offer personalized diet and training plans based on their findings. They claim that this service, which costs about $200 and up, can help people make more meaningful lifestyle changes to help them get stronger, fitter, faster and healthier. "There is so much information out there about how to lose weight or get fit," says Dan Reardon, the CEO and co-founder of Fitness Genes. To actually get the results you want, he continues, "you have to be able to know what will work for you."
Sounds pretty good, right? I thought so, too, which is why I was so excited to dig into my results when they showed up online a few weeks later. But before getting into those findings—and exploring the science in the field—it's important to understand how the testing itself works.
The promise of genetic testing is that it can tell you more about the way you're built, so that you can tailor your lifestyle to fit your biology.
We all know that everyone inherits genetic material from both their mother and their father, which becomes a unique chemical blueprint, called DNA. This DNA makes up our more than 20,000 genes, which each carry instructions for a single protein, that together determine how we look and how our bodies function. All of our genes are gathered into 23 chromosome pairs, found in almost every cell in our bodies. Genetic tests typically look at specific chromosomes, genes or proteins, and changes or mutations that occur within them, to make determinations about disease or disease risk, body processes or physical traits. Direct-to-consumer tests, which are conducted outside of the medical setting, use cells found in the saliva to reach these results.
When it comes to diet and nutrition, my results revealed that I have what FitnessGenes calls an "increased obesity risk" allele on my FTO gene, which Reardon says is likely to make me eat more, feel hungry soon after a meal and crave fattier foods than someone without this allele. Sound familiar? According to FitnessGenes, about 40 percent of people have the same genotype as me, and another 14 percent have two "increased obesity risk" alleles—more than half the population combined. To counteract this finding, he told me, I should count calories and eat four or five small meals a day to keep my natural cravings in check, and make sure that I'm burning off more than I'm consuming.
These recommendations are essentially common sense of the eat less and move more variety—plus a push for resistance, strength and high intensity interval training, which SELF readers have been encouraged to include in their workout plans for a while. But after completing the marathon (with a finish time 15 minutes faster than my pre-kid race almost nine years earlier), I decided to give them a try. As I did so, I also dug into scientific research and spoke with experts to determine whether a test like this could help people who are similarly committed to improving their health achieve the results they want.
Test results can be fascinating, but experts aren't so sure that they're all that useful—at least not yet.
The first question I wanted to answer was simply, is the science there yet to make valid recommendations based on this type of test? Claude Bouchard, Ph.D., director of the human genomics laboratory at Pennington Biomedical Research Center in Baton Rouge, was unequivocal: not by a long shot. "When it comes to these current genetic tests for fitness and performance, they have almost zero predictive power," he says.
The FTO gene, for example, is actually just one of more than 100 genes that have been associated with obesity, Bouchard says. When all of them are viewed together, they can only explain about 3 or 4 percent of obesity risk. Lifestyle and environment play a big role in this complex equation, so when you view that obesity-risk allele on the FTO gene, for which I have one, the difference between me and a person who has zero risk alleles is a couple of ounces, Bouchard says. People with two risk alleles are on average less than two pounds heavier than people without them, he continues.
The same tenuous relationship between these genes and disease risk or sports performance holds true across the board, he says. A group of 23 geneticists from around the world agreed, as they wrote, along with Bouchard, in a consensus statement in the British Journal of Sports Medicinein September. The key takeaway: Although this field has grown tremendously in recent years, the science is still in its earliest stages, and at the moment, tests relying on it hold no value.
That doesn't mean that we won't get to solid science on this topic though someday, says Bouchard, who's worked in this field for almost 40 years. "We've made a lot of progress in the last few decades. We know how to ask the questions better and we have better technologies," he says, but there needs to be more research before results from this sort of test are validated. The fact that the National Institutes of Health is now funding a major project in this field is a good start, he says.
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