We all have that one friend who can eat anything and never workout without any negative consequences. On the other hand, there’s the friend who eats healthy and is active but may still gain weight. How much of this can be attributed to genetics and how much does environment play a role? To further explore this scenario, we’ll have to get scientific, but don’t worry, this is more fun than high school biology class so keep reading! So let’s find out who wins in the battle of Diet vs. DNA.
Round 1: Epigenetics and Nutrigenetics
Try not to get lost in the facts as we delve into the vast world of epigenetics and nutrigenetics. Epigenetics is the study of the changes and differences in organisms based on how certain genes are expressed. Nutrigenetics is the study of how these gene expressions are affected by nutrients. Utilizing the information gained from these areas of study, we can optimize health through the prevention and treatment of diseases and personalized nutrition.
Round 2: Genes Make a Difference
We all know that what and how much we eat affects how much we weigh. But did you know that new research is emerging that shows us that having the right genes can also make a difference? Scientists have performed several research studies involving the Apolipoprotein A-1 (APOA1) gene. (Try saying that five times fast.) This gene is an important protein component of high density lipoprotein (HDL) in plasma. HDL is the ‘healthy’ cholesterol we want in our bodies. The APOA1 promotes the flow of cholesterol from our body tissues to the liver for filtration and excretion.
Scientists have showed that the APOA1 gene is associated with certain deficiencies and diseases and can significantly affect how a person’s body reacts to what they eat. If you have a defect in your APOA1 gene, it is advised that you watch your intake of saturated fats. For example, research shows that people with a certain version of this gene, when consuming a high-fat diet, had a significantly higher body mass index (BMI – a measure of a person’s fat mass based on their height and weight) than those without this specific form of the gene. The APOA1 gene is a great example of how nature and nurture both play a role in body weight. More research is necessary to help tailor diets to individuals based on their specific DNA and environmental factors.
Round 3: Environment Also Plays a Factor
Clearly what we eat matters when it comes to our weight, however, our genes also matter. Certain genes, like those that code for eye color or baldness, are not directly affected by our environment. Other traits are the result of our DNA PLUS the environment. Height and your likelihood of tearing an ACL have been correlated to specific genes. However, based on your environment, these genes may never come into play. For example, a malnourished child may never get the chance to reach his/her full height potential and a sedentary person may never be in a situation where an ACL tear is possible.
Round 4: Blame Mom & Dad
There are 20,000 human genes and only hundreds of these genes have been studied carefully and with respect to exercise. Several genes are correlated to aerobic fitness, muscular power, and adaptability to training. While you may have been dealt a less-than-ideal set of genes, we can always improve on what we have.
The significant differences between yourself and other people is based on your genes and the concept of heritability. Heritability refers to how much of the differences can be blamed on genetics and how much can be attributed to exercise and training. The higher the heritability percentage, the more we can attribute differences to our genetics. Obesity, for example, is 70% heritable. This means that genes play a significant role in our chances of being overweight. However, we can change this through our environment with diet and exercise. Heritability can also explain why following the exact same exercise program with a friend may yield significantly different results when starting from the same fitness level. We cannot necessarily change the shape of our muscles, but we can change the size of our muscles through exercise, or lack thereof.
And the Winner is…
Based on the information we currently have on Diet vs. DNA and body shape, we know that genetics are not the only influencer of BMI. This means that nurture does have an effect of nature, but how much exactly? Presently, we don’t precisely know. As more research studies are conducted, we will have a better understanding of who wins the biological struggle of Diet vs. DNA in relation to exercise and our environment.
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Written by Sarah Brunner, RDN, CD; Elite Sports Clubs Registered Dietitian
Sarah is certified in food allergies/intolerances and nutritional counseling, Academy of Nutrition and Dietetics; has a certificate in Dietetics from Mount Mary University; and a BA in Education and Mathematics from the University of Wisconsin – La Crosse.