Can your DNA be your ‘secret weapon’ for nutrition and fitness?


Several companies promise that by looking into your DNA, you can unlock the secret to weight loss and fitness. But do these tests deliver? So far, results seem mixed

The weight-loss and fitness businesses are huge industries that make significant financial gains each year. Marketdata, a market research firm that has tracked the U.S. weight-loss market and published in-depth reports since 1989, reported in December 2017 that such programs continued to grow. The commercial weight-loss programs segment of the market was worth $2.77 billion in 2016 and was forecast to grow 9.4% to $3.03 billion for 2017. And the International Health, Racquet & Sportsclub Association announced in its 2017 report that in the United States, the fitness industry saw an increased revenue of 7.2% (from $25.8 billion in 2015 to $27.6 billion in 2016).

Simply stated, people in the United States spend big on weight-loss, weight-maintenance, and fitness services and products. And new options for losing weight and staying fit continue to pop up each year.

One of the newest offerings is DNA testing as a tool for weight loss. The companies that offer these services say that DNA testing can be helpful to find the right way to lose weight. But do these tests deliver useful results? So far, reviews seem mixed.

Nutrigenomics is an emerging science that uses molecular tools to better understand how different people respond to diet and exercise. Some companies, such as FitnessGenes, Habit, and Nutrigenomix, are tapping into this science to provide people with insights into their DNA – and how they can apply this knowledge to their diet and exercise routines.

One such company is Helix, which through its embodyDNA service provides DNA-based advice that “is broken down into simple and actionable recommendations that you can start implementing on day one.” You provide a saliva sample to get your DNA sequenced and get recommendations for what to eat and foods to try.

Habit, another company, also cites how the nutrition-related genetic markers you are born with lay the foundation for your results (for example, how your body handles fats, carbs, and protein through a time sequenced set of tests). DNAFit, another testing service, provides more information on its site, explaining how we metabolize nutrients, deal with toxins, and react to different types of exercise in our own unique ways. It explains in detail the role that 38 different genes can play in how you metabolize nutrients and respond to exercise.

Interesting as the DNA insights may be, how much of a difference do they make for weight loss and optimal fitness? While genetics play a role, it may not be a major one. Even Helix on its own website notes that “your genetics play a part, but your diet and exercise choices have the biggest impact on your weight.”

A 2015 article on nutrigenomics research, published in Applied and Translational Genomics, points out that there is potential in the tools, but the results from tests are not necessarily indicative that this is how your body works. The article notes that many studies lack definite associations between the genes and outcomes, so they’re only one clue, not certain contributing factors.

Still, the companies offering these DNA tests tout results via case studies and testimonials, with customers citing weight loss, increased energy, and better sleep. But writers who have tried such services seem willing to give the DNA insights only partial credit for their success. In the May 2016 issue of Shape Magazine, writer Anne Machalinski writes about her experience getting a test through FitnessGenes, which looked at 42 genetic markers. Based on her results, she was advised to count calories, eat smaller, more frequent meals to combat cravings, and make sure to burn off more than she consumed.

“Can I attribute my weight loss and physical changes to [the company’s] recommendations?” she writes at the end. “There’s no way to tell. Following common sense advice of ‘eat less, move more’ may have gotten me the same results.“

Writing for Live Science in February 2018, Cari Nierenberg takes a more direct stance with an article titled “Why You Probably Shouldn’t Waste Your Money on DNA-Based Diets.” Nierenberg acknowledges that the concept of following a diet “that’s tailored to your own unique genetic makeup instead of trying a one-size-fitsall approach” seems like a good idea, but it doesn’t make much of a difference.

The article cites a Stanford University study, published that same month in the Journal of the American Medical Association, that shows that a person’s genes do not in fact affect how well a diet may work. Researchers, the article states, “found that overweight adults who followed a low-fat or low-carbohydrate diet tailored to their genetic predisposition and biological makeup weren’t any more successful at shedding pounds than the groups that followed the same two diets, but without the customization for these predispositions.”

Because the science is still relatively new, subsequent studies may show different results. Still, for people looking to do these tests, it’s probably best to not look at this as an end-solution. And as always, it’s best to consult your doctor, dietitian, or other healthcare expert for any new diet or exercise regimen.

One DNA testing company that incorporates this aspect is Nutrigenomix. The Canadian biotechnology company, launched in 2012, provides its Nutrigenomix test kits through healthcare professionals. Like the other services, it uses saliva samples to provide clients genotyping and customized reports.

But instead of providing the results directly to consumers and letting them figure out how to implement the information, Nutrigenomix is available exclusively through professionals such as registered dietitians. This means when customers get the information, they have a nutritionist explaining the results. Will this approach be better than the direct-to-consumer testing? Only time can tell.