How to Calculate Your Macronutrient Needs, According to Traditional Nutrition Educators

This article explains how to calculate your macronutrient needs according to traditional nutrition educators, that is, the view that most energy requirements of athletes should be obtained from carbohydrates. Discussion of similar calculations based on low carb high fat, or LCHF, diets such as the Banting method will follow in the next article. For now, however, I’ll stick to ratios suggested by most nutrition courses, although a burgeoning volume of evidence is building that this may not be an optimal situation, even detrimental to the health of individuals in many cases.

In the previous article, I have set out how to calculate your total daily calorie need, using Jason, a 24-year-old male strength athlete with a body weight of 100 kg as an example. Based on his resting metabolic rate (RMR) and physical activity level (PAL), Jason needs 3,271 calories daily to fulfill his energy needs and maintain current weight. Next, Jason has to determine how to acquire that energy by working out his macronutrient needs, or how much carbohydrates, protein, and fat he should consume daily.

Carbohydrate Intake

Most educational material and teachings agree that carbohydrates should provide the bulk of an athlete’s energy needs. Based on “The Complete Guide to Sports Nutrition” by Anita Bean, guidelines for daily carb intake for different activity levels are as follows.

To determine the most appropriate activity level, use these distinctions to inform the decision:

  • Light – A recreational athlete with training frequency 3-4 times a week for up to one hour a session, and a light-moderate intensity
  • Moderate – A competitive athlete with training frequency 5-6 times a week for one to two hours a session at moderate intensity
  • High – A competitive athlete with training frequency 6-7 times a week for two to four hours a day at a moderate-high intensity
  • Very high – An ultra-endurance athlete training 6-7 times a week for more than four hours a day at a moderate to high intensity

Continuing with Jason as the example to illustrate the calculation method, as he does strength training 4-5 times a week at a light to moderate intensity, we decide to select 5g per kg body weight as his most appropriate daily carb intake target. Therefore, for him, at 100 kg body weight, 500 g of carbohydrates are required daily. As the calorie content of carbohydrates is 4 kcal/g, Jason’s energy provided by carbohydrates is 2,000 kcal or 61% of his total daily calorie need (3,271 kcal/day).

Next, we determine the best protein consumption.

Protein Requirement

Regarding the protein requirement of athletes, a few things are of immediate interest. The World Health Organization (WHO) recommends a minimum daily protein intake of 0.8g/kg body weight per day. According to recent reports, the global average daily protein consumption is 77g per person, but the number for sub-Saharan Africa is far lower at 55g per person. However, the protein needs of athletes and others who participate in regular physical activity are higher and their protein needs also differ depending on their goals and type of sport. Although this is a discussion for another time and worthy of a separate article, according to some scientific evidence, there is no discernible body composition or performance benefits associated with a daily protein intake higher than 2g/kg body weight. The authors of “Practical Applications of Sports Nutrition” propose the following guidelines for protein intake.

So, Jason, as a strength/resistance athlete not on a fat-loss or weight-gain program, should consume 1.5 to 2.0 g/kg of protein per day. This comes to a range of 150 to 200 grams for his body weight of 100 kg. At a calorie content of 4 kcal/g, his protein intake provides 600-800 kcal per day. Finally, using it as a balancing factor, we calculate the fat intake requirement.

Fat Intake

Before showing the calculations of fat intake target, it is good to note some important facts. At 9 kcal/g, fat is very energy dense, more than twice compared to carbohydrates and protein, meaning that the same grams of fat provide 2.25 times more energy. Fat intake is essential for body functioning and health and has a variety of critical contributions, including acting as a carrier for fat-soluble vitamins and antioxidants, insulating the body, providing a reserve of energy, forming a protective layer for the organs, involved in producing hormones, and forming brain tissues and nerve cell membranes. Although no recommended daily allowance (RDA) is set for total daily fat intake, the consumption of fat should not be below 15% of total energy intake with most health institutions and departments proposing a range of 20-35%.

Keeping these guidelines in mind – and discounting, for now, evidence to the contrary by low-carb high-fat nutrition proponents – we aim to ensure that our fat intake falls within these parameters. This means, for Jason, that there are between 471 and 671 kcal left to come from fat after subtracting calories from carbs and protein from his total target of 3,271 kcal per day.

To recap, his carb intake target is 2,000 kcal/day and his protein intake target range 600-800 kcal/day.

Therefore, the lower fat target is (3,271 – 2,000 – 800), or 471 kcal/day of fat.

Similarly, the upper fat target is (3,271 – 2,000 – 600), or 671 kcal/day of fat.

Expressing these targets in grams of fat:

Lower fat intake = 471/9 = 52g/day [Reminder: fat has a calorie content of 9 kcal/g]

Upper fat intake = 671/9 = 75g/day

The final check and balance are to confirm that his fat intake target is not below the recommended range. Of his total daily calorie requirement of 3,271 kcal, 61% comes from carbs, 18-24% from protein, and 14-21% from fats. As the lower fat number is below the recommended minimum, Jason’s targets will be set according to the upper range, that is, 2,000 kcal from carbs (61%), 600 kcal from protein (18%), and 671 kcal from fat (21%).

In the next article, I will review the calculations from an LCHF or Banting diet perspective, which means considerably dropping the carb intake target, increasing the fat intake target, and, although the LCHF guidelines don’t specifically address protein intake levels, probably increase the latter toward 2g/kg of body weight. That’s it for now, folks. I welcome any questions or comments via email, website, or social media.

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Joan Swart is a master's powerlifting enthusiast, sports nutrition student, and forensic psychologist from Paarl, Western Cape.

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