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Getting Personal: How Does DNA Affect Your Nutrition?

Getting Personal: How Does DNA Affect Your Nutrition?

Reading Time: 5 minutes 54 seconds


DATE: 2020-02-17

Anyone who has ever struggled to lose weight, and the trainers working with them, knows that there is no single best diet or nutritional plan that works for everyone.

A big reason for that is our individual genetic makeup. With modern technology we can now take simple tests for specific genes. This information helps explain some of the struggles people experience regarding nutrition, health, and weight.

Everyone has a unique genome that impacts everything from how we utilize protein and fat to whether we absorb enough iron from the foods we eat. Knowledge of these individual differences is a powerful tool.

If you have clients interested in taking health or fitness DNA tests for personalized reports, it's important that you know what to do with the results. Find out what these reports tell you about a client's nutritional needs and limitations and how to use that information for their benefit.

DNA and Nutrition - What is Nutrigenomics?

Being able to look at an individual's genetic makeup is now less expensive and more accessible than ever. Any one of your clients can get a test done that looks specifically at how their genes impact nutrition, health, fitness, body composition, and more.

Nutritional genomics, or nutrigenomics, is the study of the interactions between an individual's DNA, nutrition, and health. It can also be a more general study of the overall human genome and nutrition. Researchers in this field look at how foods and nutrients impact human genetics and how genes inform the body's response to nutrients.

How Does Genetics Affect Nutrition? And How Can That Help Clients?

While researchers are working to uncover generalities about the human genome and nutrition, it is also possible to get individualized data. For trainers and clients, it is this personalized information—how one or more genes or mutations in genes impact how we absorb micronutrients, gain weight, or utilize macronutrients—that is important.

With a fitness and nutrition DNA report for a client, you can pick out the information that will help determine goals and strategies for meeting them. Personalized genetic information will help you:

  • Set goals that are more reasonable for each client

  • Recommend macronutrient ratios that make sense for a healthy weight and body composition

  • Create nutritional plans that consider vitamin or mineral processing or uptake issues

  • Create a workout and diet plan for more effective weight loss

DNA Tests and Nutrient Utilization

A client's DNA-based nutrition report will include a lot of information about how they utilize nutrients, including macronutrients, vitamins, and minerals. Genetic differences can lead to variations in how these nutrients are absorbed, how they are used, and the proportions and amounts that maximize health and wellness.


Weight loss and maintenance, energy utilization, athletic performance, and more depend on how we consume and utilize proteins, fats, and carbohydrates. Most recommendations for macronutrient proportions are generalized, but DNA tests inform more personalized macro ratios.

  • Protein. Most people have a "normal" genotype for protein utilization. Those who do should consume about 15 to 30 percent of daily calories in the form of proteins. Their ability to lose weight will not depend on protein intake. The less common "enhanced" genotype means that an individual will be able to lose weight more effectively and efficiently with a higher proportion of protein in the diet, about 25 to 30 percent.

  • Fat. As with protein, most people fall into the "normal" category for fat utilization. Their weight loss seems to be independent of the percentage of fat in the diet if calorie intake is reasonable. Those who test for the "low" genotype should consume a smaller proportion of fat, about 15 to 25 percent of daily calories. This will aid in weight loss and maintenance.

  • Carbohydrates. For carbohydrate utilization, there are three genotypes: "normal," "enhanced," and "low." Those in the "normal" category will see no major differences in weight loss based on carb proportions. The "enhanced" genotype means that a person benefits from eating more carbs, up to 65 percent. But note that these should be complex carbs, like whole grains and beans. In the "low" category, people should eat fewer carbs and be especially careful to avoid starchy foods and processed grains, such as potatoes and white bread. The glycemic index is a good tool to help these clients choose better carb sources.


Less important for weight loss, but still crucial for overall health, is information on micronutrient utilization. Most health and fitness DNA tests provide data on Vitamins A, B6, B9, B12, C, and D as well as calcium, iron, magnesium, and zinc.

Certain genotypes can tell you if a client is absorbing and utilizing these nutrients adequately. This is important to know for health but can also be useful for nutrition and weight goals. For instance, some people have a "low" genotype for B12, which means they tend to be deficient. Low levels of B12 cause a type of anemia, called pernicious anemia. This can lead to serious health risks and make working out more difficult due to fatigue.

A genotype that makes it more likely for an individual to have low levels of calcium means they are vulnerable to osteoporosis. Again, this can lead to serious health problems but also interferes with fitness. Weak bones can be broken more easily during training activities.

One of the best ways to ensure an adequate intake of micronutrients, both vitamins and minerals, is to eat a diet rich in a variety of vegetables. Talk to your veggie-resistant clients about how important this is for health and weight maintenance.

Nutrition and Genetics and the Impact on Disease Risk and Health

Of course, DNA reports for nutrition are important for more than simply meeting weight loss goals. Your clients also come to you for advice on a healthy diet to avoid disease and to live well. These reports are packed with different types of information to help you advise them more effectively.

How Does Genetics Affect Nutrition and Health Measures?

Certain health measures, like cholesterol, are impacted by genetics as well as diet. For instance, you may have a client with a "sensitive" or "highly sensitive" genotype for cholesterol response to dietary fat. This means their cholesterol levels tend to increase more rapidly with fat intake as compared to someone with the "normal" genotype. They need to be more careful about the fat content in their diets.

You can also learn about an individual's insulin response to dietary fat. Certain genes and mutations lead to greater insulin sensitivity with fat in the diet. Most people have better sensitivity with a lower-fat diet, but there are exceptions. Those with the "highly sensitive" genotype, for example, benefit from eating up to 40 percent of their calories from healthy fats.

Diabetes is a major public and individual health problem in the U.S. You may have clients come to you with this disease or at risk for it. Understanding insulin sensitivity and response can help you help them make better food choices to control blood glucose levels.

Polyunsaturated fats, like omega-3 fatty acids and alpha-linolenic acids, are the so-called healthy fats. The body does not make these fats, so how much a person has in their bloodstream largely depends on diet. Some genes, however, also make an impact. Although common, the "normal" genotype for this is not ideal. Clients with this result really need to focus on adding healthy fats to their daily meals.

Avoid Giving Medical Advice

When you use DNA reports to help guide nutrition choices for clients, you run the risk of providing medical advice without being qualified. This is especially true for advice related to health risks and chronic disease.

You can absolutely provide guidance on how to plan and eat a healthy diet for both weight goals and overall health and wellness. You cannot advise clients to use their diet to treat or manage any kind of chronic illness, though. If you are at all unsure about where to draw the line, err on the side of caution. Recommend they see a doctor for specific medical advice.

The use of individualized DNA reports is poised to revolutionize health, wellness, and fitness. Personal trainers need to be a part of this big change. You can take more personalized, molecular, and genetic information for each client and help them adapt their lifestyles, diets, and fitness routines for better results. Make sure you understand these reports, how to use them, and how to communicate the results with clients.

Clients today expect their trainers and nutrition coaches to be up to date on all the related science, including genomics. To be able to better help clients and to add a new certification to your credentials, check out the ISSA's online DNA-Based Fitness Coach course.

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