The allure of personalized nutrition, guided by the intricate blueprint of our DNA, has captured the attention of many seeking to optimize their health and achieve their weight loss goals. Genetic tests promising to tailor diet and lifestyle recommendations based on individual genetic makeup have become increasingly accessible. But what can these tests really deliver? This article delves into the science behind DNA tests for weight loss, examining their potential benefits, limitations, and the existing research in this rapidly evolving field.
The Promise of Nutrigenomics: Can Genes Guide Our Diet?
The field of nutrigenomics explores the interaction between genes and nutrition, aiming to understand how individual genetic variations influence the way our bodies respond to different foods and nutrients. There is promising genetic research in many areas of nutrition, from DNA methylation, to phytosterol and cholesterol absorption, to dietary fat metabolism. The ultimate goal is to personalize dietary recommendations based on an individual's genetic profile, optimizing their health and well-being.
Polygenic Risk Scores: A More Comprehensive Approach
As the Human Genome Project revealed, the human genome contains between 20,000 and 25,000 genes. A single nucleotide polymorphism, or “SNP,” is the most common type of genetic “mutation” found in people. We all have variants in shared genes which cause small changes in enzyme activity, or in the case of rare genetic disorders, the loss of function altogether. Genetic risk scores (GRS), also called polygenic risk scores, have the potential to be more reliable than the current study of one SNP at a time. Most nutrigenomic markers standing alone don’t determine health outcomes in the same way that a single gene disease, as with cystic fibrosis. GRS will be a part of the future of personalized medicine and nutrition and studies are already showing that GRS has greater efficacy than just placing people on one size fits all diets like Keto.
DNA Diets: A Personalized Approach to Weight Management?
DNA diets are designed by teams of scientists using different genetic markers, with different weighting based on the strength of the research for that gene. Just as mutual funds are built using baskets of stocks, DNA diets are built using polygenic risk scores. The power of what we do is rooted in the sheer number of SNPs we score, a number which is always increasing as new research emerges, plus how we combine several polygenic risk scores to arrive at the core diet type.
The Importance of Diversified Risk Scores and Long-Term Studies
One of the core problems with “DNA diet” studies, as well as the reporting on them, is the failure to differentiate between the use of a single SNP vs. a polygenic risk score. A study, highlighted by Dr. Peter Attia on his blog, found DNA diets were no more effective than “one size fits all” calorie restriction for weight loss looked at just 10 SNPs. That study lasted only 12 weeks. The BMC Nutrition Study I review below found efficacy for weight loss with a genetically tailored diet, but the results took 18 months!
Read also: The Ultimate Guide to Male Diet Supplements
Examining the Evidence: Do DNA Diets Really Work?
While the concept of tailoring diets to individual genetic profiles is appealing, the scientific evidence supporting the effectiveness of DNA diets for weight loss remains mixed. Several studies have investigated the impact of genetically tailored diets on weight management and other health outcomes.
A UK Study: Ketogenic vs. DNA-Tailored Diets
Researchers in the UK compared a ketogenic diet vs. a DNA tailored diet for maximum nutrition. The 114 subjects were monitored in two stages: a 24 week initial stage and then an 18 month follow up. Initially, members of the ketogenic diet group lost on average about 2.5 more kg than the nutrigenomic group, who were placed on a low glycemic index DNA diet similar to our Forager diet. After 18 months, the weight loss for the DNA diet group was significantly higher than the ketogenic diet group, who saw significant weight gain after the 24 week sprint. After a year and a half, the DNA diet group had lost on average 8 kg more than the ketogenic diet group. Further, the DNA diet group had significantly better results in lowering total cholesterol and fasting glucose, and in raising HDL. The nutrigenomic group had better adherence than the ketogenic diet group and were given an exercise program tailored to their genetics as well. By contrast to the JAMA study cited by Scientific American which looked at only 3 SNPs, the BMC study evaluated 28 SNPs and 22 genes. Notably, the BMC study increased dietary folate intake for those with MTHFR SNPs and gave them a B complex supplement with 400 mcg of folate (unclear whether methylfolate was given). The use of 28 SNPs to form a polygenic risk score, as opposed to trying to gauge outcomes from a single SNP, is a step in the right direction, and inevitably contributed to the success seen by the DNA diet group. However, the BMC study again has the fatal flaw of a lack of diversity. All the participants here were European Caucasian.
The Circulation Study: Gene-Diet Interaction and Insulin Resistance
This study, which appeared in the Journal Circulation, a publication under the auspices of the American Heart Association, found that variants in the IRS1 genes (specifically IRS1 rs2943641 CC genotype) can benefit from a higher carbohydrate and lower fat diet to combat insulin resistance. The Circulation study evaluated 738 subjects over 2 years and saw improvements in both insulin levels and weight loss for those assigned to a DNA diet protocol. For me, the Circulation study was particularly interesting because it may shed light on which genotypes can utilize plant based diet protocols to combat high blood sugar, and conversely, which people might do better using a lower carb approach to insulin resistance and type 2 diabetes.
The DIETFITS Study: A Reality Check
A team at Stanford University found that genes cannot predict who might lose more weight on certain diets. The study, called DIETFITS and published in the Journal of the American Medical Association by researchers at Stanford University Medical School, randomly assigned 609 overweight adults, aged 18 to 50, to either a healthy low-fat or healthy low-carb diet. The volunteers got 22 hourlong classes with dietitians on healthy low-fat diets (eat less oils, fatty meats, full-fat dairy, and nuts) or low-carb ones (reduce cereals, grains, rice, starchy vegetables, and legumes), as well as on the dangers of eating mindlessly. Both groups were instructed to eat lots of vegetables and very few foods with added sugars, trans fats, or refined flour. There was virtually no difference in weight loss between the two groups after 12 months: 11.7 pounds in the low-fat group and 13.2 in the low-carb one, a difference that was not statistically significant or meaningful in real life. The researchers then analyzed weight loss among people whose DNA “matched” or clashed with their assigned diet. That was based on which variants of three genes-called PPARG, ADRB2, and FABP2, which are involved in processes such as fat and carbohydrate metabolism-they had. Earlier research suggested that these variants could predict who would successfully lose weight on which kind of diet. “There was no significant difference in weight change among participants matched vs mismatched to their diet assignment,” the researchers wrote. There was also no DNA/diet interaction for waist circumference, body mass index, or body fat percentage.
Concerns and Limitations of DNA Diet Tests
Despite the growing interest in DNA diets, several concerns and limitations need to be considered:
Read also: Meal replacement guide for women
Lack of Standardization and Diversity
First, there is no one uniform DNA diet. The studies on efficacy are mixed and they almost exclusively look at weight loss rather than cardio-metabolic health. Further, the BMC study again has the fatal flaw of a lack of diversity. All the participants here were European Caucasian.
The Complexity of Gene-Diet Interactions
Dozens or even hundreds of genes contribute to traits such as eye color, hair color and height. The risk of heart disease, cancer, and your propensity to gain weight, are even more complicated. There’s no such thing as a single “fat gene.”
Misinterpretation of Results
Complicating the issue is the fact that raw genetic information is difficult to interpret, so genetic testing companies offer third-party interpretation services to help you wade through the test results. This can leave you confused and possibly fearful, which could contribute to a whole cascade of negative effects [14]. For example, if you have a SNP that’s linked to obesity, you may assume that you have no control and will automatically develop a weight problem, which may decrease your motivation with lifestyle interventions.
Environmental Factors and Lifestyle Choices
The truth is, environmental factors are far more important when it comes to body weight and weight loss (and other health outcomes) when compared to our genetic predisposition [5].
Alternatives to DNA Diet Tests: Evidence-Based Strategies for Weight Loss
Rather than spending your healthcare dollars on a weight loss DNA test that’s unnecessary and unhelpful, I would rather you use well-studied interventions that are known to be effective for weight loss like a well-balanced diet plan and exercise. These are the same interventions that will benefit you the most in the end, whether you’ve had genetic testing or not.
Read also: Chlorine Brand Comparison
Intermittent Fasting (IF)
When it comes to weight loss specifically, research has found IF can lead to significant weight loss for people with excess weight [20].
Exercise
Resistance training incorporates exercises that use all muscle groups of the body. I recommend both cardiovascular and resistance training as this combination approach is likely most beneficial for health overall [28, 29]. If you’re new to exercise, you may want to start with 1 day of cardiovascular exercise (brisk walking, running, cycling, elliptical) each week and 2 days of resistance training.
Gut Health
Research suggests that people who carry extra weight may have leaky gut [30]. If you’re hoping to lose weight and body fat, I recommend zeroing in on your gut health. Many of the solutions I use for healing your gut overlap with traditional (and very effective) weight loss recommendations like healthy eating and exercise.
Popular DNA Testing Companies: A Closer Look
Several companies offer direct-to-consumer DNA tests for diet and wellness, each with its own approach and offerings. Here's a brief overview of some popular options:
23andMe
DNA testing company 23andMe provides a comprehensive, science-based test. To its credit, this pioneer of direct-to-consumer genetic testing doesn’t make promises that don’t hold water. It does not claim to tell you what to eat or how much to exercise, and provides a huge amount of medical information as a bonus.
Vitagene
A rival company, Vitagene, tells me something similar. “You may lose less fat in response to a low-fat diet compared to others,” my Vitagene report reads.Vitagene recommends I take 10-15 mg of zinc a day for “energy levels” and body weight.
DNAfit
DNAfit claims to provide some of the most comprehensive DNA testing available. The company also states that it can provide unrivaled insight into users’ diet, nutrition, fitness, and well-being. However, some of the health claims they make are unsupported by evidence, and there’s little scientific evidence for DNA-based personalization. For these reasons, we don’t recommend purchasing or using DNAfit kits.
Everlywell
Overall, Everlywell has a solid reputation besides the criticism about their controversial food sensitivity testing. They also use Clinical Laboratory Improvement Amendments (CLIA)-certified laboratories, so you’re sure of quality service and results.
myLAB Box
Like Everlywell, myLAB Box offers a convenient way to test for STIs and other health conditions from the comfort of your home. In addition, they offer free shipping and results in as little as 2 to 5 days.
FoodMarble
FoodMarble uses a type of breathalyzer that claims to help you figure out which foods cause digestive issues. The device is small and portable, so you that can take it with you on the go.
SelfDecode
As a result, SelfDecode’s Weight Report analyzes thousands of genes and over 455K genetic variants total. You can’t give someone truly personalized results when all you’re looking at is a few genetic variants.