January 28, 2021
There are now many companies that will analyze your DNA and reveal what your genetic code says about you.
You can use your DNA to trace your family history or find out if you are more susceptible to various health conditions. Some companies even claim to be able to tell you which diet might suit you best based on your genetic makeup.
But can a genetic test tell you the best way to eat? We don’t think so, and here’s why.
Your genes are encoded within DNA, which is found in almost every cell in your body. They are the biological instructions that enable you to develop, grow, and function on a day-to-day basis.
Each of us has around 20,000 genes and - unless you have an identical sibling - your DNA is unique to you.
Your genes are responsible for some inherited traits, such as how tall you are and what color eyes you have.
However, most of your characteristics depend on more than just your DNA. For example, your genes alone do not determine how fit you are or how much you weigh, whether you will develop certain conditions like heart disease, cancer, or diabetes, or how your body breaks down and uses food.
All this, and much more, depends on how your genes interact with your environment, your daily habits, and the trillions of bacteria that live on and in your body (your microbiome).
It all adds up to create the unique tapestry that makes you who you are.
Although they’ve found some genetic variations that increase the chances of developing some of these chronic diseases, most of the evidence so far suggests that genetics plays a relatively small role. Other factors, such as your weight and age, are much better predictors of risk.
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Weight loss research has repeatedly shown that different diets work for different people. Some people will lose weight on a low-carb diet, while others fare better following a low-fat diet, making individual diet recommendations difficult.
This variability has made some researchers wonder whether genes might play a role. However, recent results from the DIETFITS study, which looked at individual responses to two different diets, found that genes have little influence on how much weight anyone will lose on a particular diet.
In our PREDICT studies, we have unraveled the complex relationships between genetics, responses to food, and metabolic health. Our trial included nearly 200 identical twins, who share almost 100% of their genes. We measured each participant’s responses to food after eating identical meals and compared their results to their twin.
If genetics play a large role in determining your metabolism, we would expect to see that identical twins have similar responses. But we saw that identical twins can have very different responses to the same meals.
Using all of our twin data, we analyzed the heritability of responses to food. We found that genetics explained just 30% of the variation in blood sugar responses to food and less than 10% of the variation in insulin and blood fat responses.
Importantly, we found that individual nutritional responses aren’t random. They are regular and predictable, but they mostly aren’t down to your genes.
Despite the lack of evidence to support choosing your diet based on your genes, many companies out there will sequence your DNA and then give you food recommendations based on your genetics. But our PREDICT study tells us that this is far too simplistic.
Our research shows that to find the foods that work best for you, you’ll need to look beyond your genes and focus on your responses to food.
We’ve discovered that a wide range of things - such as your microbiome and when or what food you eat - can predict your metabolic health and your responses to food much more strongly than your genes. Your stress levels, how much you exercise, and how well you sleep also play an important role.
This is good news. Unlike your genes, all of these factors are under your control, so you can take action to improve your metabolic health. You are not a prisoner of your genes.
That’s why when you take our at-home test, we go much deeper than your DNA, analyzing your microbiome and measuring your unique responses to food.
Our tests give an accurate picture of your current metabolic health, giving you truly tailored recommendations for foods that work with your biology and help you take back control of your health and weight.