Should You Have Genetic Testing Done Before Starting A Diet? Here's What We Know

The field of genetic testing has moved from being a quirky means of understanding your ancestry or a helpful tool for uncovering your risk for disease to including lifestyle and health advice that could allegedly hold the key to successful diet plans and weight loss. With the advent of companies like 23andMe, Vitagene, Helix, Orig3n, and DNAFit, it's safe to say that people are curious about whether they should do a gene test before starting a diet. You swab the inside of your cheek for a saliva sample, mail it off to one of these companies, and wait for a specialized recommendation. 

It's called nutrigenetics, the idea that your genes have an effect on how you metabolize dietary nutrients and how you respond to exercise. According to registered dietitian and one of the faces behind the nutrigenetics company Genotique, Sheri Maltais from Toronto (via CBC), "We all have a unique response to food and what works for one may not work for another." Proponents of nutrigenetics think that this is why some people find it harder to lose weight and why others can eat whatever they want and not gain weight. 

Apparently, you could veer away from the one-size-fits-all approach to healthy living and find something that actually works for you, all based on your DNA. Understandably, this approach to genetic testing and diet plans has been met with some resistance.   

The problem with diet plans based on genetic testing

There are health professionals who are concerned about the lack of substantial data to support the definite premise that genetic testing can be your miracle answer when it comes to a successful diet plan, mainly because the research on nutrigenetics is still in its infancy. As explained by adjunct professor of nutrition in the Harvard T.H. Chan School of Public Health's nutrition department, Dr. Lu Qi (via TODAY), while the goal of genetic testing to come up with personalized diet plans is promising, it's too early to be making recommendations.

One of the larger studies that critics of DNA-based diets widely cite is a 2018 study published in JAMA Network that involved 609 overweight adults, aged 18 to 50, who went on either a low-fat or low-carbohydrate diet for 12 months (via STAT News). After the year was up, researchers not only found that there was a negligible difference in the fat loss between the two groups (the low-fat group had 11.7 pounds of weight loss and the low-carb dieters had 13.2 pounds of weight loss), but that their DNA genotypes (low-carb genotype vs low-fat genotype) had no influence on the results. 

This is not to say that your genes don't play a part in weight loss. It's just that there isn't enough to go on based on large-scale randomized controlled trials, shared Dr. Aaron E. Carroll, pediatrician and author of "The Bad Food Bible" (via The Doctors). What does this mean for starting a diet plan? 

Start with what you do know, say the experts

According to Dr. Aaron E. Carroll, per The Doctors, the concept of using genetic testing to come up with a diet plan is almost too complicated when compared with what science has already uncovered and is readily available to you. "We don't need any genetic test to know that people should lead a healthier lifestyle. They should exercise, they should eat a well-balanced diet, they should not smoke, and they should not drink too much." 

The idea of having your DNA test done to give you personalized answers, while interesting, might not be definitive, according to Larry Brody of the National Human Genome Research Institute (per NBC News). With about 20,000 protein-coding genes in the human genome, it's safe to say that there's a lot more to uncover. Not to mention that there are reports of people receiving varying recommendations from different genetic testing companies.  

It might be wise to start your diet with the basics: plant-based foods, whole grains, protein, and healthy fats. Consider working with a registered dietitian to assess your diet (e.g., if your weight loss efforts aren't working). Choosing a diet that's best for you might also be a process of trial and error. It might involve your particular needs, your budget and finances, the time you have available for exercise, and even health considerations (per Mayo Clinic). Ultimately, it's about finding a diet that you follow with consistency, which is key when it comes to getting the results you're after.