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Protein, Carbs, and Fat: How DNA Affects Macros in Your Diet

Protein, Carbs, and Fat: How DNA Affects Macros in Your Diet

Reading Time: 7 minutes 18 seconds


DATE: 2020-03-09

Nutrition coaches and personal trainers are equipped with more information to help their clients than ever before. In addition to all the research into weight loss and health, you can now get personalized information about each client you work with.

Genetic testing is increasingly popular, and if you work with clients in health and fitness, you must stay up to date. If they haven't yet, clients will begin asking you about genetic tests and how they can use them for weight loss and other fitness goals.

One area of nutrition with a lot of individual variation involves choosing macronutrient ratios. Certain ratios of protein, fat, and carbs work well for most people in a particular situation, like those trying to lose weight, improve insulin resistance, or put on muscle mass. However, you can't reach everyone with the same strategy. A genetic test can tell you more about an individual, how they process macros, and their ideal intake ratios.

Why Use Genetic Tests with Clients?

The most important benefit of using genetic testing with clients is that it provides you with information. This kind of test will not give you all the answers, but it does offer more details about multiple factors that impact how an individual metabolizes nutrients, craves food, and gains or loses weight.

With this information, a good personal trainer or nutrition coach can take some of the risk and guesswork out of finding the right way to help a client. We already know that one diet or fitness plan cannot possibly be optimal for everyone. Each person is unique, and without genetic information, determining the best plan requires a lot of trial and error.

Even with genetic testing, you'll still be doing some educated guessing, assessing, and making changes. But, the initial plan you create will be more targeted, and hopefully more successful in meeting a client's goals. With the right information from listening to clients, and from their genetic test results, you can identify the barriers, risk factors, strengths, weaknesses, and challenges each client faces in trying to hit nutrition, weight, and other health goals.

Why Are Genetic Factors Affecting Macros in Your Diet Important?

Macronutrients—protein, fat, and carbohydrates—make up the bulk of our diet. In addition to many other functions in the body, they provide us with the energy needed just to live and function. Normal growth and development, as well as other health factors, depend on getting adequate amounts and the proper balance of these nutrients. But what is the right amount of each? Turns out, it depends on genetics.

Science Proves We're All Different

Everyone responds uniquely to the same foods and diet. Nutritionists and coaches have long known this, but recently a big study proved it. Called the PREDICT study (1), it included over 1,000 participants. More than half of these were identical twins with the same genetics.

The researchers followed the participants' diets and measured several health and wellness factors throughout the study. The responses to the same foods varied widely by individual. While the study did not consider all the potential environmental factors that could account for differences, it did conclude through the study of twins that about one-third of the variations could be attributed to individual genetics.

Macro Ratios Vary for Both Populations and Individuals

For most people, general recommended amounts and ratios of macros in the diet can be followed for good health and to maintain weight. But, not everyone responds the same way to the same diet. Special groups may need different ratios, like people looking to lose weight or build muscle.

Special situations, such as weight loss, may call for shifting ratios of macros in the diet, but individual genetic differences may also be important in making tweaks. Genetic information can tell you how a client utilizes each macronutrient, how their weight responds to various ratios of macronutrients, how body composition changes in response to macro amounts, and more.

What makes a diet successful for weight loss? It can be confusing when there are so many diets advertised, especially for your clients. Read up on the three basic elements that lead to weight loss.

Protein Utilization

A standard health and fitness, sometimes known as lifestyle, genetic test can provide you with information about how your client uses protein. With this information, you can better determine an appropriate daily percentage for protein intake with their specific goals in mind.

High-protein diets, like a paleo or ketogenic diet, are popular now. Many people use them to lose weight, to build muscle, or both. The gene known as FTO can provide information on how well these diets will work for an individual client. The test can also help you determine an appropriate amount of daily protein intake for them.

Amino acid supplements are increasingly popular for weight loss. But do they work? We'll give you the rundown here on using branched-chain amino acids to lose weight.

The "Normal" Genotype

If you work regularly with clients and genetic tests, you'll realize that most fall into the normal category. This means that they don't have the variation in FTOthat causes body mass and composition to change relative to protein intake.

In other words, these clients may not see much difference in weight loss or fat loss by upping protein. The recommended daily protein intake for these clients is 15 to 30 percent of total calories. Those who are more active should be on the higher end.

The "Enhanced" Genotype

These are your clients who will benefit from eating a greater percentage of protein. They have genetic variants that trigger greater weight loss with more protein in the diet. These people should aim for getting 25 to 35 percent of the daily calories from protein.

This may seem like the lucky group, but there is a downside. They also tend to lose lean muscle when losing weight. For these clients, you need to be strict with strength training and make sure they do it regularly to avoid muscle loss and to enhance fat loss.

Fat Utilization

Too often clients will assume that fat is bad, that they should avoid it at all costs, especially for weight loss. Fat, just like protein and carbs, is an essential nutrient. It is important for cell structure, hormonal signaling, vitamin utilization, and for making foods satisfying and helping you feel full.

The typical American diet is much too high in fat. While it is necessary in the diet, the foods readily available to us also make it far too easy to overindulge. Striking the right balance with the other macros and between types of fats maximizes health and weight loss goals. Several different genes are tested to determine the fat genotype.

The "Normal" Genotype

Again, most people have the so-called normal genotype for fat utilization. This means that as long as they stick with a dietary plan with a sensible number of calories, the amount of fat consumed will not impact weight loss or maintenance. These clients can consume between 20 and 35 percent of their calories as fat, including no more than ten percent saturated fats.

The "Low" Genotype

With this genotype, a client has some unfavorable variations in the fat-related genes. They are more sensitive than others to types and amounts of fat in the diet. Eating too much fat triggers more stored body fat and weight gain in these people. On the other hand, reducing fat in the diet can promote weight loss. They may benefit from a low-fat diet, defined as 15 to 25 percent of daily calories.

Carbohydrate Utilization

While fats have long been the bad guys of weight loss, dieters in recent years have found a new villain in carbs. Low-carb diets are popular for losing weight, but it's important to remember that carbohydrates are essential for energy and other aspects of health.

Some people also avoid carbs in the hopes of preventing insulin resistance and diabetes. It's true that higher amounts of simple carbs, like sugar and refined grains, can cause spikes in blood sugar and eventually insulin resistance. But research indicates that the quality of carbohydrates consumed is more important than quantity (2). Tests of the IRS1gene can clue you in to how your clients respond to carb intake for health and weight.

The "Normal" Genotype

For most people who have a normal genotype, weight loss will not vary depending on the percentage of carbs in the diet. This may be disappointing for those clients who hoped to use high-protein, low-carb diets to lose weight. As a coach, it's your job to explain that counting overall calories and focusing on high-quality carbohydrates will benefit their weight and health.

The "Enhanced" Genotype

The carb-lovers on your client list will be thrilled to get this result. The "enhanced" genotype indicates that a person will have better weight loss or maintenance results with a high-carb diet, about 65 percent. On this diet, clients should restrict fat to 20 percent and focus on high-quality carbs while avoiding refined grains and sugar.

The "Low" Genotype

Clients in this category really can benefit from a low-carb diet that is richer in protein, healthy fats, and vegetables. They will have more weight loss success with fewer carbs in total and by almost totally avoiding processed, refined carbs and sugar. A useful tool for these clients may be the glycemic index. Show them how to use it to choose better carb sources.

What is a Coach's Scope of Practice with Genetic Testing?

As you work with a client's genetic results and try to optimize their nutrition, keep in mind your limitations as a coach. Your job is to listen to clients, determine their needs and goals, and work with them to make nutrition recommendations.

When you start getting into genetics, clients may want to talk about disease and health issues that are firmly outside your scope of practice. Any time a client's needs veer into the medical, take a step back and suggest they see their doctor. A nutrition coach is an educator and guide and plays an important role in helping people live healthy lives, but they are not medical professionals.

With that in mind, you're ready to take your clients to the next level with nutrition coaching. Help each individual get the most out of their nutrition with the results of genetic macro testing.

Are you a certified nutrition coach yet? What are you waiting for? It's easy to get certified when you study online: check out the ISSA's course for becoming a Certified Nutrition Coach.


1EurekAlert. (2019, June 10). When it Comes to Food, One Size Doesn't Fit All: World's Largest Scientific Nutrition Research Project Reveals Even Identical Twins Have Different Responses to Food. Retrieved from https://www.eurekalert.org/pub_releases/2019-06/mcg-lsn060719.php

2Ludwig, D.S., Hu, F.B., Tappy, L., and Brand-Miller, J. (2018). Dietary Carbohydrates: Role of Quality and Quantity in Chronic Disease. BMJ, 361:k2340. Retrieved from https://www.bmj.com/content/361/bmj.k2340

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