Can a DNA Test Really Help You Lose Weight?

We are all unique. Put a thousand people on the same weight loss diet and you will see a number of results. Some will lose a lot, some will lose a little, and some losers will even gain weight.

Science still cannot tell us why some people lose weight more easily than others. Maybe we each have our ideal diet and we just need to find it. Maybe people who are gaining weight on a Mediterranean diet just need to try keto, and vice versa. In truth, few diets are successful in the long run, but we all keep looking, “Maybe I just need to find a diet that works for me.”

Perhaps the clue to who is who lies in our DNA. Scientists are constantly finding the connection between genetics and nutrition. For example, Inuit in Greenland have genes that can help their bodies recycle their culture’s traditional high-fat diet. Meanwhile, many of us have a variant of a gene called FTO that increases the likelihood of being overweight. However, studies have shown that diet and exercise can reduce the effect of the FTO gene on body weight.

We live in the future, so of course you can take a genetic test to find out which variant of the FTO gene you have. And why stop at just one gene? Companies like Habit , Arivale , DNAFit, and even the calorie counting app Lose It combine genetic insights with coaching about what to eat. Costs range from $ 20 to hundreds of dollars, plus a one-time DNA read fee, which is usually $ 80 or more.

The only problem with this approach: Scientists studying nutritional genetics believe that it is too early to base dietary recommendations on your DNA. For example, this FTO gene has been shown to produce a difference in body weight of only a few pounds.

But the commercial offer is very tempting. “The only thing we’ve always been wrong is that we’ve always taken a one-size-fits-all approach to food,” laments Habit founder Neil Grimmer inhis TEDx talk . (The habit uses DNA results along with blood tests to provide nutritional advice and sell meal plans.) “I believe 2017 will be your era. The era of personalization. The era when we look inside ourselves to answer the question: “What products are right for us?” “

But there are limits to what we can learn by looking within ourselves. So far, the tools that allow us to examine our DNA, and the research that helps us interpret it, are not accurate enough to tell exactly what is going on.

How Genetic Nutrition Testing Works

Our DNA’s encoded messages are billions of letters ( nucleotides ) long, but personalized nutrition companies only care about a few of those letters – from tens to hundreds, depending on the product. You will find out which “variant” you have in each of these regions of your DNA. The sites themselves are known as single nucleotide polymorphisms or SNPs (pronounced “scissors”).

SNP is a convenient, well-researched shortcut to genetic variation. Scientists interested in the FTO gene, for example, have oftenlooked at a single location on chromosome 16, codenamedrs9939609 . For any area of ​​DNA that a scientist might want to study, there is likely a known SNP in or near that area.

We have two copies of most of our chromosomes, one from each parent, so your genotype in a given SNP consists of a two-letter code representing the nucleotides on each chromosome. On rs9939609 I have one A and one T.

There are two main ways that genetic testing companies can find out what SNP variants you have, and both start by sending a bottle of saliva to the lab. If you send it to AncestryDNA or 23andMe, they will use a microchip-like device to test hundreds of thousands of SNPs simultaneously. If you send it to Helix, the partner lab for many of the new weight loss services, they will actually read millions of emails from large chunks of your DNA, but they will keep the entire dataset under wraps. You can then allow a partner company like DNAFit to ask Helix for some of your SNPs.

Many companies that provide DNA-based diet advice offer you both: you can let them view your Helix data, or you can download a file from a genotyping service like 23andMe. Helix charges $ 80 for a one-time sequencing fee. 23andMe and Ancestry currently offer genotyping with the option to download a data file for $ 99.

I started researching this article when Lose It offered me to try their new genetic testing feature for free, including paying a $ 80 Helix sequencing fee. The service, dubbed EmbodyDNA, currently sells for $ 109 . I later bought my own analysis from Arivale – it is now $ 19 – because I was curious to see how they compare.

I am listing the current prices because all these companies seem to be trying to change their prices, which change from week to week. On a lucky day, you might even waive sequencing fees.

The results you get

“We did a lot of interviews about embodyDNA and a lot of reporters were predisposed to some interesting [results],” Lose It’s Kevin McCoy told me during our interview. Before calling, I sent him screenshots of my results. “And I think you are definitely more prone to normal.” In other words, my results were boring.

EmbodyDNA is the name of the Lose It genetic testing product. I can view my results on a dedicated screen in the app, separate from the calorie counting functions. A total of 19 results were obtained, five of which are related to weight loss. Among other things, I learned that I was likely to have normal vitamin D and iron levels, and that I was unlikely to have lactose intolerance. My DNA says that I am probably a super taster, which makes me sensitive to bitter tastes, and that I am a “slow” metabolizer of caffeine, which means I can enjoy the effects of a strong cup of coffee for hours after I drink it. … As far as I know, this is all true.

Only two of my findings were surprising enough to be potentially useful. One said that I can lose weight through exercise. Perhaps all the same. But, as a rule, for most people, exercise plays a very small role in losing weight . “Your genes give you the added advantage of achieving your weight loss goals,” the app told me. It also said that 57 percent of the world’s population shared this trait, giving me a small majority.

Another unexpected finding was in the fitness section: “Your genes suggest you have more slow-twitch muscle fibers,” the screen said, “which can help you maintain activities like running long distances for a longer period of time without fatigue “. Based on this result, it seems to me that I should prefer endurance exercise over sprint.

The problem is I know the output is wrong. I get terrible results in long distance racing and generally hate every minute of it. But I love sprint and my time is always surprisingly good for someone of my skill level. I have no doubt that I am a sprinter.

So, I looked for the scientific data behind this. My result was based on just one SNP,rs1815739 . A 2003 study in the American Journal of Human Genetics found that my variant is rare in elite Australian strength athletes, but more common in their endurance-focused counterparts.

There was nothing in the study to suggest that this gene was relevant to ordinary people, and of course there was no reason to believe that an amateur athlete like me should switch to another sport because of this. … Sports performance is influenced by many factors, both biological and others. The type of muscle fibers can be one of them, but there is also the size and shape of the muscles, heart and lung function, psychology (what if you hate certain sports?), And more. A 2014 review of the genetics of athletic ability concluded that “several genes are invariably associated with high athletic performance, and none of them is strongly linked to warrant their use in predicting athletic success.”

How DNA Test Results Can Become Weight Loss Advice

Even though I already had my doubts about the usefulness of genetic data, one late evening I found myself browsing the Helix store . Arivale, best known for its $ 199 / month intensive health education service , has offered a DNA test to help you “beat your genes” and lose weight for as little as $ 19. Of course, why not?

Both Arivale and embodyDNA worked with the same saliva sample I submitted to Helix, so any differences between the two would be due to interpretation, not something that happened in the lab.

There were a few differences because the services use different SNPs for their conclusions:

• Arivale says I have an increased risk of having a high BMI. EmbodyDNA says I am at medium risk.
• Arivale says that I am more likely to get better if I have saturated fat in my diet. EmbodyDNA states that saturated fat is unlikely to affect my BMI.

And some similarities:

• Arivale says I’m unlikely to gain weight from a high-fat diet; this applies to fats in general, not just saturated fats. EmbodyDNA states that a low fat diet is unlikely to affect my BMI.
• They both agreed that exercise can affect my weight loss results, but everyone talks about it differently. Arivale thinks that I have a bad result: I will most likely get better if I lead a sedentary lifestyle. But EmbodyDNA is giving it a positive boost, arguing that physical activity is likely to help me lose weight.
• Both agreed that I was probably sensitive to bitterness.
• And both agreed that I was not particularly sensitive to the taste of sugar.

I actually have a normal BMI, but like most people, I would not mind losing a few pounds. I taste bitter food a lot, but over the years it has subsided, and I even had a snack on black licorice. (I tried one of those bitter tests a few years ago and definitely fell into the delicate category.)

The next step is to figure out what to do with this information. EmbodyDNA uses your food tracking data to make in-app automated recommendations. For example, people who are sensitive to bitter taste dislike certain vegetables, such as cabbage. So the app looks through my diet history to find nutrient-rich vegetables that I really like and prompts me to eat more.

Arivale offers a consultation call to a registered dietitian to help sort out the results. My coach started the conversation by talking about how I currently eat and exercise, and what my goals are. We then looked at the results, and for each of them, she started by asking me if this was consistent with my experience. We worked together on practical tasks, such as discussing which foods I would like to add to my diet and which ones I would not mind.

In the end, her recommendations seemed pretty reliable. We have agreed on specific goals:

• Increase the amount of exercise because my results indicate that exercise will benefit me.
• Eat More Vegetables – Since I am sensitive to bitterness, I need to make sure I don’t avoid vegetables.
• Swap the saturated fats I usually eat (I chose butter) for olive oil and other healthy fats.

At first, the joint discussion seemed to me a good sign: she does not consider these DNA results to be my destiny, but asks me to think about what my real life experience taught me. Her recommendations were completely in line with standard dietary guidelines, so there was nothing too weird. But then I realized – we could have had almost the same conversation without the results of the DNA test.

When I asked companies about the importance of genetic data in their products or coaching, they tended to downplay the importance of it. DNAFit sent me a statement saying, “Our nutritionists and trainers will have a holistic view of each individual, guided by their genetic makeup, but also taking into account each individual’s goals and past history.” If I bought the complete Arivale program or subscribed to the Habit service, I would be asked for other tests, such as a blood test. Erin Chernkovich-Barrett, a scientist at Habit, says the company never uses genetics alone to give weight loss advice. She summarizes the approach by saying, “DNA is just part of your story.”

Genetic testing has not been shown to help people lose weight

“I don’t think we’ll find someone with a genetic profile who thinks [they] have to eat marmalade to lose weight, and they just didn’t know about it,” says Christopher Gardner , a nutritional researcher at Stanford. “Or they should have been eating cupcakes and they didn’t know it. Or they really need to eat chocolate chip cookies to lose weight and they didn’t know it. ” No matter how personalized your diet advice is, you’re not getting something that is drastically different from what we all know about healthy living : more vegetables, more exercise, and so on.

Gardner led the DIETFITS study, which hoped to confirm that a specific combination of genes would determine whether people lose more weight on a low-carb or low-fat diet. But when the results were published, it turned out that the subjects’ genetic profiles were not related to their chances of success .

During the study, the following SNPs were tested:rs1801282 ,rs1042714, andrs1799883 . They are variants of genes that appear to be involved in metabolism, and previous research has shown that people with one version of these genes may respond differently to their diet. Alas, it didn’t work out.

But Gardner agrees with a fellow researcher who joked that the study had just disproved one out of a million possible SNP combinations, so now the number has dropped to 999,999. “This is very cynical. We didn’t just do something random. We thought about it a bit. But he is right: there are many different options, and you cannot compare them all with each other in the study. “

Studies like DIETFIT are rare because they require you to tell people what they need to eat and then track them to see if they are following instructions and losing weight as a result. They are terribly expensive; no one is going to fund 999,999 such lawsuits.

Instead, much of the research that has already linked SNPs to real health conditions is based on larger studies that look at populations of people – perhaps hundreds of thousands – and compare their DNA to medical records or survey responses. These studies are a snapshot in time, so they can tell you that people with a certain genetic variant are more likely to be overweight. But they don’t provide any clue as to why these people get fat, let alone what happens when they go on a diet.

Insufficient Evidence for Weight Loss Claims

There is a paradox in personalized nutrition: studies that link genetic data to health conditions are reliable, but they are not tests of real-world results, such as what happens when you go on a diet.

It seems that the scientists and company representatives I spoke with for this article understand this. They happily sent me studies when I asked about the evidence, they acknowledged the limitations of science and explained that they phrased their statements carefully so that no one saw direct promises of weight loss. But that caveat seemed a bit unrelated to what’s going on here in general: people buy genetic testing kits to learn how to lose weight.

(Helix, LoseIt / EmbodyDNA, and Habit were interviewed. DNAFit sent in a detailed statement. Arivale did not respond to my request for an interview for this article, but my health coach Arivale has shown a good understanding of the limitations of science and volunteered to send me research so I can read more .)

If you read about weight loss genetics, you will find that many SNPs have been suggested as potential players. The idea is that tens or hundreds of genes each contribute a little to your weight by adding or subtracting a few potential ounces. Sometimes genetic testing companies combine this data to tell if you are predisposed to being overweight or not. (Again, you can just step on the scale.)

But when it comes to the interactions between genes and diet, or genes and exercise, one SNP appears all the time:rs9939609 from the FTO gene. It is one of the most studied genes in this area, and it is very important. Instead of adding a few ounces of fat, it gives people an average of two to four extra pounds.

This gift can be reduced through exercise or dietary changes, which sounds promising. But Ruth Loos, a researcher who is also the senior author of one of the big papers on the FTO gene and physical activity , noted that the effect is very small. Exercise only increases the FTO contribution by about 30 percent, from one kilogram per allele to 700 grams. In other words, exercising with one risk allele (like mine) will reduce your weight by an average of 300 grams. Less than one pound. And that should be my key to losing weight?

Loos thinks companies are going too far. “It really annoys me when people use this kind of research to turn it into predictions.”

Technically no. Helix has a strict anti-low science policy and sets out what advice partner companies are allowed to make, including EmbodyDNA, Arivale, Habit and DNAFit. Basically, they can explain your results and make expert suggestions, such as saying that your health coach thinks you need to eat less oil. But they are not allowed to predict results unless there is research to support the recommendation. When it comes to weight loss, this level of research simply doesn’t exist.

Weight genetics

Genetics alone cannot explain why some people are fat and others are thin. Loos estimates that body weight is half your genes and half the world you live in, including what you do and what happens to you. Half may seem significant enough for genetics to be a useful predictor, but there is a problem: within the 50 percent or so that is genetic, the percentage we can explain with known genes is in single digits.

A 2015 study of 97 genetic variants known to affect body weight concluded that together, they can only explain less than 3 percent of individual differences in BMI.

We also don’t even know what many of these genes are doing inside our body. The FTO gene was originally found in mice that lacked many genes and had a deformity with fused toes as a result. Even today, researchers are unsure whether the FTO gene produces a protein that affects body weight, or if another gene is responsible, and that rs9939609 is nearby is just a coincidence.

Ethnicity is another issue for any purported connection between genetics and diet. In many large genetic studies, people of European descent are more common than representatives of other nationalities, so there is no guarantee that these results will mean the same in other populations. Kevin Klatt , nutrition researcher and doctoral student at Cornell University, explains why ethnicity matters:

• The SNP that appears in the results may not be part of an important gene , but may just be nearby in the people who participated in this study. But in another group of people, this SNP and this gene may not be linked at all, making the SNP useless as a marker of what the gene is doing.
• Other genes matter . Maybe there is a gene associated with a particular SNP and that gene is causing the disease. In one population, this could be the whole story. But in a different population, people can usually have a completely different gene that protects against the same disease. This can hide the influence of the first gene on the disease, making it unimportant.
• The environment matters . The world around us can make the effects of the gene more or less noticeable. For example, a gene called MTHFR affects how well our bodies use a vitamin called folic acid. But research shows that in some countries this gene has a stronger effect than others, depending on whether the food in that country is fortified with folate, as in the United States.

Ideally, genetic research should receive data from people around the world. It recruits participants from rural and urban areas, all races, rich and poor, etc. But until this is the case, anyone underrepresented in the research may get less reliable results.

However, research continues, and it is possible that someday we may be able to explain the full 50 percent of the causes of weight gain, instead of just 3 percent. But what are we going to do in the meantime?

How to use genetic data (if you like)

First, don’t believe it. I think these words sound ridiculous, but even the companies themselves dance around the words about losing weight, because there is no evidence that following their recommendations will make you thinner.

This means your results are good for two reasons. First, they can be the source of healthier habits. You could do worse than talk to a trainer who will advise you to exercise more and eat less oil. For some of my geneticists, this is not the only way to lose weight, but just as good as any other. (After all, any diet works as long as you stick to it .)

“The recommendations [of these companies] are usually harmless in the sense that they [are] the recommendations that any nutritionist or any kinesiologist will give anyway,” Loos says. “Like,” You need to exercise more and eat less. ” So it’s just a business opportunity – selling your typical recommendation as a more innovative package. “

Another way to use your results is through your own curiosity and perhaps starting an experiment with one person. “I’m in n from one study,” Gardner says, referring to the number of participants in the trial. In other words, experimenting with yourself. “Try [recommended diet] and then stop doing it,” he suggests. “Or try the opposite and see if it works.” Take notes and draw your own conclusions. (Gardner may want to study self-experimenters in the future. If that’s you, contact him at [email protected].)

In any case, you will have to treat your genetic findings like a horoscope. Pick the parts that feel right to you and hug them; then quickly forget about the rest. And in personalized nutrition – as in life – base your decisions on more than one source of information.