Understanding Macronutrient Needs

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A Dietitian-Approved Series for Distance Athletes

Understanding Macronutrient Needs

Authors

Katie Knight, Nutritional Sciences Master's Student at Texas Tech University (TTU) &

Marleigh Hefner, Registered & Licensed Dietitian & Nutritional Sciences PhD Student at TTU

Introduction & Welcome Back

This is the second article of our blog series covering nutrition topics specially designed for distance athletes. Please be sure to read Article #1 if you have not done so already to learn important nutrition basics, as well as how to calculate approximate total calorie and water (fluid) needs for this unique group of individuals.

Many coaches, parents, and runners are already familiar with the term macronutrients, often referred to as "macros." Macronutrients are nutrients the human body requires in relatively large quantities to supply energy. These include carbohydrates, protein, and fat. It is vital for distance athletes to consume the correct ratio of carbohydrates, protein, and fat for the optimization of athletic performance. In this article, we will discuss the function of the 3 macronutrients and teach you how to calculate carbohydrate, protein, and fat requirements for endurance runners. As a reminder, these recommendations are merely a starting point and do not take into consideration unique medical conditions. Any athlete who is managing their calorie and macronutrient intake should be monitored by their registered dietitian nutritionist (RDN), coaches, teammates, and family for any unintended outcomes (e.g., weight loss or gain).

Protein

Protein is a frequently discussed macronutrient in the strength training world for good reason: it is essential for muscle growth and recovery, maintaining fluid balance, immune system health, and many other functions (1). Protein is made up of building blocks known as amino acids. Every cell in the body requires protein for its growth, function, and survival. While protein is important for strength athletes, it is equally (if not more) important for distance athletes. Though expert opinions vary, research suggests that endurance athletes may require more protein than their resistance training counterparts (2). However, consuming too much protein can be detrimental to the kidneys, especially without proper hydration. Thus, it is important to consume the correct amount of protein to total calories. In general, distance runners require more protein than most other populations to maintain necessary muscle growth, recovery, and health. A dietitian-approved guideline for optimal protein intake for endurance athletes is 0.73 grams of protein per pound of body weight per day. So, to calculate total daily protein needs in grams, multiply the athlete's body weight (in pounds) by a factor of 0.73. Using an example athlete who weighs 130 pounds and wants to maintain current muscle mass, this athlete would need approximately 95 grams of protein per day: 130 x 0.73 = 95. It should be noted that athletes seeking muscle growth instead of maintenance or who wish to lose weight while retaining muscle mass require even higher amounts of protein, up to 1.0 grams per pound of body weight.

In addition to total quantity of protein, recent research also suggests that protein consumption can be further optimized by ensuring protein is consumed in regular increments throughout the day. This is based on the theory that the human body can only effectively metabolize a certain volume of protein at one time, which is proportional to body mass, while the rest is left unused and often excreted through urine. To address this phenomenon, it is recommended to consume roughly 0.2 grams of protein per pound of body weight across a minimum of four meals per day (3) which will come close to the general recommendation of 0.73 grams of protein per pound of body weight daily. For example, a 130-pound athlete requires approximately ~26 grams of protein per meal or snack: 130 x 0.2 = 26.

Finally, it is also important to consider the quality of protein consumed. Nutrition experts use the Protein Digestibility Corrected Amino Acid Score (PDCAAS) to determine protein quality and how thoroughly different sources of protein will be utilized by the body. We recommend using the PDCAAS to guide your athletes' protein choices at meals or snacks. For example, cow's milk, soy protein, eggs, and beef have a high PDCAAS score, so these are high-quality protein choices for endurance athletes. 

Carbohydrates

Carbohydrates are essential to human life and are the body's preferred source of energy, especially for distance athletes whose sport demands high levels of intense energy utilization. Hence, carbohydrates are absolutely critical for distance runners to promote ideal performance. Another reason we emphasize the importance of carbohydrates for distance athletes is because carbohydrates are protein sparing. If carbohydrate intake is too low, the body will synthesize glucose from protein for energy through a process known as gluconeogenesis. So, consuming enough carbohydrates can prevent muscle degradation because all the protein consumed in the diet can be used for muscle growth and repair, rather than for energy. A few great sources of carbohydrates include fruits, starchy vegetables, and whole grain products, such as breads, cereals, and pasta.

The body stores carbohydrates in the body as long chains of glucose referred to as glycogen. Glycogen is stored mainly in the liver and muscles so that glucose can be quickly accessed and broken down for energy. Carbohydrates are particularly vital for distance athletes for not only its protein-sparing quality, but also its ability to prevent exercise-related perceived fatigue (1). Notice the graph provided by Fink & Mikesky (2018) which shows us that as exercise time increases, muscle glycogen stores exponentially decrease, while perceived fatigue exponentially increase. This graph highlights the importance of adequate carbohydrate intake leading to optimal glycogen stores, which prevents fatigue in sports where prolonged exercise is required.

With this information in mind, let's finish this section by practicing how to calculate carbohydrate needs. Our recommendation for distance runners is approximately 2.5 grams of carbohydrate per pound of body weight (1). So, to calculate the total daily amount of carbohydrates needed, simply multiply the athlete's body weight in pounds by a factor of 2.5. To keep with our same example, a cross-country athlete weighing 130 pounds needs ~325 grams of carbohydrates per day: 130 x 2.5 = 325.

Fat

Consuming enough dietary fat is important for general health, such as promoting healthy skin, hormone production, and the absorption of fat-soluble vitamins (1). However, we will spend the least amount of time focusing on dietary fat requirements for runners because this macronutrient is not as critical to performance as protein and carbohydrates. Instead, we recommend following heart-healthy guidelines recommended by entities such as the American Heart Association or the Dietary Guidelines for Americans. Endurance athletes-and the general population-should aim to reduce the amount of saturated fat consumed and replace this with unsaturated fats. Saturated fat is fat that is generally solid at room temperature (e.g., butter), whereas unsaturated fat is more fluid at room temperature (e.g., olive oil). Distance athletes should generally select reduced-fat varieties of animal products where applicable, such as low-fat dairy and lean red meats and poultry. Other healthy sources of fat include nuts, seeds, and fish.

Our dietitian-approved recommendation for ensuring your distance athlete is consuming enough dietary fat is to simply to use fat to "fill in" the rest of total daily calorie needs (after calculating calories provided by protein and carbohydrate). To do so, first subtract the number of calories provided by protein and carbohydrates from the total daily recommended calories. For example, a 130-pound athlete with energy requirements of 2210 calories per day, 95 grams of protein per day, and 325 grams of carbohydrate per day can convert these units from grams into calories by multiplying by a factor of 4. This is because protein and carbohydrates both have 4 calories per gram. Next, divide the remaining number by a factor of 9 to determine the approximate grams of fat needed per day. This is because fat contains 9 calories per gram. Below is a step-by-step example to help clarify the math.

Step 1. Subtract total daily calories from calories provided by carbohydrates and protein

• 2210 calories - (95 grams of protein x 4 calories per gram) - (325 grams of carbohydrates x 4 calories per gram) 

• 2210 calories - (380 calories from protein) - (1300 calories from carbohydrates) = 530 calories left for fat

Step 2. Divide the calories left for fat by 9 to calculate grams of fat recommended per day

• 530 calories left for fat / 9 calories per gram of fat = 59 grams of fat per day 

Concluding Remarks

Congratulations, your macronutrient calculations are complete! You should now be able to understand the importance of a balanced, nutrient-rich diet containing the correct ratios of carbohydrates, protein, and fat for endurance athletes. Our next article will cover pre- and post-workout nutrition recommendations, in addition to important micronutrient considerations for distance runners.

Correspondence: Marleigh Hefner RDN, LD (holistic.nutrition.science@gmail.com)

References

1. Fink H and Mikesky A. 2018. Practical applications in sports nutrition. 5th ed. Burlington: Jones & Bartlett Learning. 

2. Tarnopolsky MA, MacDougall JD, Atkinson SA. Influence of protein intake and training status on nitrogen balance and lean body mass. J Appl Physiol . 1988;64(1):187-193. doi:10.1152/jappl.1988.64.1.187

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