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DNA Diet In 2021: Does It Work?

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Yes, a DNA diet, meaning a diet that takes your unique genetics into account, can work if you are looking at the right genes to address your dietary concern. A very simple and straightforward example of a diet that takes your genetics into account is the PKU (phenylketonuria) diet. It’s a diet based on only one genetic variation: a mutation in the gene that encodes for a protein which helps build an enzyme needed by your body to breakdown phenylalanine. Come again? It’s a mutation that causes your body to not process phenylalanine properly. Oh, okay. And what’s phenylalanine? In addition to being a spelling nightmare, phenylalanine is one of the 20 amino acids your body uses to build protein. Long story short, if the mutation ultimately takes away the ability of the body to breakdown phenylalanine, it builds up causing some serious damage if left untreated. How do you treat it? Great question! Through diet. The PKU diet is a diet that limits phenylalanine; since it’s an amino acid, it’s found in protein foods. So, meats, poultry, fish, dairy, beans nuts, etc. are off limits. A PKU diet consists of low-phenylalanine veggies, some low protein pastas and rice, and nutritional shakes and supplements to help ensure people get all the other amino acids and nutrients they need. If the diet is followed, those with the genetic mutation can expect to have a healthy, normal life.

I used the PKU diet example because it’s easy to demonstrate the point. But chances are, most people wondering whether a DNA diet “works” are wondering more along the lines of: Will a comprehensive analysis of my DNA be able to provide me with optimal dietary recommendations? That’s the million (dare I say billion?) dollar question, and I do believe that we will get there one day. But that day is not today.

Why? Because to have a genuinely optimal diet based on your comprehensive DNA, we would have to first know how each gene (and all their unique variations) that make up human DNA affect all aspects of diet, and the science is not there yet. So, where is it then? Still emerging, but also making headway when it comes to determining the interplay between genetics and diet on more focused topics such as the PKU example above, vitamin deficiencies and usage, and weight loss ability. Before I dive into promising research on just how well DNA diets can work, let’s define what a DNA diet is and how these types of diets are created.

What Exactly is a DNA Diet?

It’s not rocket science. Or molecular biology (cheesy, I know). A DNA diet is just a diet based on your DNA. That’s it really. The complexity lays in determining which genes (and which of their variations) have the capacity to impact a particular outcome and which diet (or supplements) can influence that interaction. Still not clear? Let’s look at the examples below.

Example: Vitamin D & Genetic Variations

Vitamin D is a nutrient best known for its involvement in bone health, but if pressed further, most people will likely not know how exactly it helps bone health or what else it does in the body. In all fairness, scientists themselves are still researching the many roles it plays in health, well beyond bone health, so we’re all kind of in the same bucket there.

But, in case you’re curious, here’s some of the things we do know:

  • Vitamin D helps your body absorb calcium by essentially telling your DNA to turn on genes that are involved absorbing calcium in your gut.
  • Through this method, vitamin D also helps your bones build themselves up, and it helps keep mineral levels in your blood in check.
  • Since vitamin D can tell your DNA to turn on certain genes, it turns out that it’s involved in turning genes on involved in many other bodily processes, beyond simply bone health.
  • Vitamin D levels have been linked to how your body handles inflammation, cell growth, neuromuscular function, immune health, and glucose metabolism, among others.

Vitamin D status continues to be an active area of study in the nutrition field, including how genetic variations can affect it. Infants often receive vitamin D supplementation, particularly when fully breastfed, to help ensure they are meeting their daily needs. However, despite supplementation, healthy infants will have varying levels of this vitamin in their blood. One scientific study aimed to determine if genetic variations may explain some of those differences. In this study, 913 healthy infants were randomly assigned to receive 2 different doses of vitamin D3 (the common type of supplement given), from 2 weeks old until 24 months old. Circulating levels of vitamin D were then assessed periodically. Guess what? There was a clear difference in the levels of circulating vitamin D level not just by the amount given (expected), but also by genetic variation (cool!). Certain genetic variations in a protein involved in carrying vitamin D in the blood affected the amount of vitamin D circulating in the blood.

What does this mean? While supplementation obviously helps make nutrients more available to the body, how much of an impact they will have can be influenced by genetic variations, and thus, diets (or supplementation regimes), catered to those variations can help individuals meet their nutrient needs. As a health professional and scientist, I absolutely recommend nutritional supplementation for certain situations, but with that said, most of the time, healthy individuals can meet their daily needs through diet. So, on that note, here are some vitamin D-rich foods to enjoy:

  • Freshwater rainbow trout
  • Salmon
  • Canned tuna
  • Herring
  • Fortified dairy milk
  • Fortified soy milk
  • Raw mushrooms

Studies on DNA Diets

Okay, so genetic variations can affect supplementation efficacy of a single nutrient, but what about a whole diet? Good question. Let’s address that beast now that you have a little knowledge on the effect of genetic variations at a basic level. When it comes to a whole diet, there are a LOT of variables to account for, and I’d be skeptical of anyone who says they have it all figured out. However, like all things “science,” it’s a long, ongoing process, but with many discoveries along the way that can already be useful to address specific concerns. Case in point? DNA diets for weight loss or improved body measurements (such as smaller waist size). Below are a few examples that are so exciting for this field!

The first scientific study found that variations in the TCF7L2 gene, a gene involved in many functions within cells and the body, including glucose metabolism, is linked to how much following a Mediterranean-type diet can affect body weight and BMI. A Mediterranean-type diet is a diet high in fruits, vegetables, and seafood; moderate in olive oil and nuts; and low in saturated fat. Researchers looked at different versions of the TCF7L2 gene in a group of Puerto Ricans in Boston. Among those who followed a Mediterranean-type diet, those with a specific, unique set of variations in the TCF7L2 gene tended to weigh less and have lower BMIs compared to those who did not have the specific variations. In essence, it may be likely that having the specific variations in the TCF7L2 gene influences how much weight you lose on a Mediterranean-type diet, a healthful diet type that is particularly lower in saturated fat.

The second scientific study takes weight loss head on using a DNA-based diet. In this study, researchers assessed overweight or obese participants who were assigned to follow a keto diet or a personalized nutrigenetic diet (diet based on assessing each participant’s DNA) that looked at genetic variations in 22 genes. While variations in some of these genes have been associated with weight loss through diet, most are associated with other dietary modifications, such as caffeine sensitivity. Thus, not all 22 genes included were related to diet-mediated weight loss specifically. The interesting finding in this study is that although the keto diet resulted in better weight loss success at 6 months (average of about 58 pounds) than the DNA diet (average of about 52 pounds), the DNA diet outperformed the keto diet in the long run. One and half years later, the DNA diet participants had continued to lose weight and had lost an average of about 60 pounds by then. The keto diet participants? They regained some of the original weight lost, so a year and half later, they had only lost an average of 43 pounds overall. This means that on the long term, the DNA diet group had lost about 17 pounds more, on average, than the keto group.

Same effort, different outcome. Wow.

And there it is. This is why we started DietCypher.

While the group that conducted the study focused on a variety of genetic variations for a variety of dietary outcomes (e.g., caffeine sensitivity as already mentioned, lactose tolerance, etc.), we ONLY focus on scientifically validated, diet-mediated weight loss genetic variations, thereby delivering the most targeted DNA diet-based weight loss approach available to date.

Why Do Some Reports Say that a DNA Diet Does Not Work?

Excellent question, and there could be many, many reasons why studies assessing the validity of a DNA diet may not “work.” Here’s a (non-exhaustive) list of reasons:

Asking the “wrong” question.

When you design a study, you need to start with an observation and a hypothesis. While that may have seemed straightforward for a 7th grade science class (or not, who’s to judge?), formulating a hypothesis can be tricky sometimes. I think now’s a good time for a friendly reminder of what a hypothesis is, which is simply a prediction. But not just any prediction (no magic fortune teller robot behind a glass for this one). No, the prediction needs to be detailed (what you think will happen under x,y & z conditions) and based on current and past observations. For example, formulating a hypothesis that orange juice is better than apple juice is a poor hypothesis, if you can even call it that. Under what conditions? Based on what observations? How do you even test that? Better at what? Taste? Nutrition? Convenience? Get my point? A better hypothesis would be to state that a cup/day of orange juice is better than a cup/day of apple juice in supplying vitamin C to elementary school children. Now this you can test. You know how much to give (one cup/day) of each test drink, to whom (elementary school kids), and you know what you are testing. In this case, vitamin C supply, which you can test by measuring the amount of vitamin C in a cup of each drink and seeing how each measure up to providing the amount of vitamin C needed within that young age group. See the difference?

Same for DNA diets. If your research study (or company) simply states that your DNA diet is “better” for you or gives you “optimal nutrition” …well, how do you test that? Versus, if you were to say that a DNA diet, based on x,y & z genes, causes more weight loss (ahem) in a certain time period versus, say, the most popular weight loss diet in the US. Now that, you can test. So, when someone says that DNA diets “don’t work.” Send them back to look at the studies they are basing this statement on. Have the researchers of said studies even defined what it means for them to “work” or be “optimal?” Have they considered what success looks like?

The wrong design.

Even among the best researchers, studies can be designed poorly, and as a result, their findings are questionable. A lot of wasted time and effort. Obviously, no one sets out to create the “wrong” design, but it still happens. For example, if you are trying to look at the presence of a gene variation between two different population groups (let’s say the presence or absence of the variation which causes red hair), you would take DNA samples from a set of people from each population group, right? Then you would compare your findings and see if there are differences. However, what if you analyzed one sample next month but then waited two years to analyze your second population sample? That’s a problem. You are introducing a new variable, time, and unfortunately, while someone’s actual DNA does not change, its integrity does. After two years, maybe all of the DNA in those test tubes have broken down (aka, gone “bad”) so they no longer give reliable information. This is a simple example to demonstrate a point. A more complex, and regarding the topic of DNA diets, a more realistic one is the very first step of the experimental design. The hypothesis.

The wrong hypothesis.

Okay, technically, there is no such thing as a “wrong” hypothesis. If you experiment shows that your hypothesis is invalid, it’s not wrong, it’s just invalid or “not true.” It’s part of science. Happens a lot. You go back to the drawing board and start again, ruling out the hypothesis you just tested. That’s how science works, people.

But with that context, hear me out. If the hypothesis is “way off,” there goes your experiment. Why? Remember that when you design and conduct an experiment, it’s to test a hypothesis, which is a prediction. So, inherently, you don’t know what’s going on…you just have an “educated guess” and design/conduct your experiment around it. If your totally out of ballpark regarding the underlying phenomena, then there’s no way your hypothesis will be appropriate to test said phenomena.

Yes, another example. If you choose to look at the effect genetic variations has on how people respond to different weight loss diets (e.g., a low carb diet versus a low-fat diet), but you pick the “wrong” genes to look at, well then, you can’t really conclude that DNA diets “don’t work.” All you can conclude is that the gene variations you chose to test do not have an effect of weight loss whether someone is following a low-fat versus a high-fat diet. And there’s no shame in that! Of course, many (okay, most?) of the genetic variations out there will likely NOT have any meaningful effect on how much weight you lose on a high fat versus a low-fat diet. Case in point? This scientific study, which got A LOT of press about 3 years ago when it was published. The researchers set out to see if variations in 3 genes have an effect on whether the participants lost weight following a healthy low-fat or healthy low-carb diet. They found no effect after 12 months. Everyone just lost weight, which ultimately is great, right? However, if you are looking at the wrong genes, then you are already grouping people into the wrong diets to test your hypothesis and well…you can guess the rest. Everyone just loses some weight, but not the maximum that they could have if the “right” genetic variations (or at least “better” indicators) would have been chosen.

I have to stop here and say that this came from a very highly respected researcher in the field and from a very highly respected institution (Stanford University), so this just goes to show that the best minds are out there working on this stuff. But in my humble opinion, they got it wrong (yes, I said it). I think they picked the “wrong” genes. I won’t go into the details why here (maybe in another blog), but in their defense, the study started in 2010 (a whopping 11 years ago!), so there have been a lot of advancements on what we know about gene-nutrient interactions since then. And while they make this clear in the publication and in the scientific community, it was not accurately portrayed in the mainstream media, which gobbled up the story and ran with it in their own way. Check it out here, or here or…you know. So, now we have a bunch of people who are skeptics, but without understanding the science.

So, How Do You Pick a DNA Diet That Will Work for You?

SCIENCE, SCIENCE, SCIENCE!!! Okay, but what does “science, science, science” look like? Well, you want to pick a DNA diet that was designed to address a specific concern. Anything that’s just “optimal” is likely overpromising. As I mentioned, our knowledge base for something that comprehensive just isn’t there yet. For example, the more reliable DNA diet may simply look at gene variations in your muscle fibers to help determine which exercise may yield you muscle mass gain, or it may look at genetic variations known to be associated with certain food intolerances. Or in our case, the DNA diet looks at genetic variations known to be involved in diet-based weight loss.

Second, you want to make sure that the DNA diet is based on sound studies, meaning that the studies were designed specifically to assess the effect of genetic variations on whatever outcome the DNA diet is supposed to address. In the case of a DNA diet for weight loss, you want to make sure that the studies used to design the DNA diet were aimed at actually addressing whether genetic variations can affect how diet type impacts weight loss. Guess what? DietCypher does that. Duh! The genetic variations DietCypher assesses were chosen using the results of randomized clinical research trials specifically designed to discover the effect of genetics on weight loss through dieting. You’d be surprised how many DNA diets are based on studies that were not specifically designed to assess the effect of genetics on that particular outcome.

Third, you want to make sure that the DNA diet is based on a healthy number of genes, not too few and believe it or not, not too many. You may think that more is better, but this goes back to point number one. If the DNA diet accounts for every genetic variation under the sun, then its efficacy may be diluted. As mentioned in point number one, the science just isn’t there yet to capture everything for an “optimal” diet. If too many variables are introduced, it may weaken the prediction model. In the simplest terms, it’s better to predict an outcome (e.g., two times more weight loss in six months) based on a few solid data points than on 25 “maybe” data points. Yes, that’s what DietCypher does. The first one, not the second one! We only look at 5 genes, but in my scientific opinion, they are the “rock star” genes for diet and weight loss. Oh, and they have been shown to significantly impact the effect of how much weight someone can lose based on which diet he or she follows. Just sayin’…Below is a quick cheat sheet on the six core diets (called DietCodes) that DietCypher predicts for someone. Some people will have additional complementary diet types, but EVERYONE will fit into one of these six broader groups.



Example Foods

01 High-Fat

Recommended for people who have genetic variations that suggest they may see the most weight loss when following a diet high in fat.

The focus is to eat plenty of healthy and essential fats.





Olive oil and plant oils

02 Low-Fat

Recommended for people who have genetic variations that suggest they will achieve the most weight loss when following a diet low in fat.

The focus is to eat nutrient-rich, low-fat foods.

Fruits and berries


White fish

Skinless poultry

Low-fat milk and yogurt

03 High-Protein

Recommended for people who have genetic variations that suggest they’ll lose the most weight when following a diet high in protein.

The focus is to eat healthy, protein-packed foods.



Greek yogurt


04 Moderate-Protein

Recommended for people whose genetic variations suggest they’ll drop the pounds by following a moderate, not high, protein diet.

The focus is to eat a “plant-based” diet including plant-based proteins and keep animal protein intake, especially red meats, in check.

Soy and tofu





Whole grains

05 High-Carb

Recommended for people with genetic variations that suggest they’ll have greater dieting success when eating a higher carb diet.

The focus is to eat high-fiber, wholesome carb foods, not refined sugars or grains.






Other whole grains (unprocessed)

06 Balanced

Recommended for people whose gene variations indicate that none of the macronutrients (fat, carb and protein) pose a weight loss advantage over the others.

The focus is a healthful, balanced diet full of variety and “super foods.”


Green leafy veggies

Almonds and other nuts


Greek yogurt



If you’re interested in learning more about how your genes and the foods you eat can affect each other, please check out our blog on nutrigenomics and nutrigenetics here.

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