CSCS Calculating Calorie Needs for Athletes | Nutrition Recommendations for Athletes

Edited by: Danielle Abel

Being able to calculate the amount of calories (energy) required for athletes is a skill you'll need to know how to perform as a strength coach. Since athlete performance is heavily dependent on adequate energy availability, knowing different types of equations you can select for different athletes, given the amount of data you have available to you is going to be key. 

3 Different Methods for Calculating

According to the National Strength and Conditioning Association (NSCA), Essentials of Strength Training and Conditioning 4th edition, they recommend 3 different methods for calculating estimated calorie intake for athletes:

• Harris-Benedict Equation
• Cunningham Equation
• Calorie needs by body weight & athlete activity level (Table 10.4)

Keep in mind that all of these calculations are going to predict the athlete's estimated energy needs, also known as total daily energy expenditure (TDEE). TDEE is the level athletes would want to eat at if they were looking to maintain their current body weight as well as their current level of muscle mass and performance. If an athlete is wanting to drop body fat, then you'll still need to calculate their TDEE, and from here, calculate their calorie deficit.

For athletes who are looking to build lean muscle, you'll also still need their TDEE to determine how much more they should be eating per day to increase their muscle mass. 

You might be wondering, well which one is best? If so, don't worry; we're going to offer some context and nuance to all 3 that might help you choose the best one for each type & situation you have with an athlete. 

Harris-Benedict Equation

This equation is best if you don't necessarily know or have access to calculate an athlete's lean mass. Meaning, you don't know what their body fat percentage is, or there's no easy way to get this data. The data you need to calculate their resting metabolic rate is:

• Age
• Sex
• Body weight
• Height

After you have their RMR, which will be reflected in calories, you'll multiply these calories by their level of activity to determine their estimated maintenance calorie needs. Keep in mind that activity level includes not only scheduled training sessions but also games/competitions and their average daily step count. 

• 1.2 = little or no exercise per week
• 1.375 = light exercise/sports 1-3 days/week
• 1.55 = moderate exercise/sports 3-5 days/week
• 1.725 = hard exercise/sports 6-7 days/week
• 1.9 = very hard exercise/sports & physical job or training 2x per day

There are several calculators available online, like this one (just make sure you select the Harris-Benedict formula from the drop-down) that make the Harris-Benedict formula below much easier to calculate:

Women: BMR = 655.1 + (9.563 × weight in kg) + (1.850 × height in cm) - (4.676 × age)

Men: BMR = 66.5 + (13.75 × weight in kg) + (5.003 × height in cm) - (6.75 × age)

Harris-Benedict Example

For example, if you're working with a 27-year-old female athlete who's 75kg and is 6'0" (183cm) tall here's how you would calculate their maintenance TDEE using Harris-Benedict:

• 9.563 × 75kg = 717.225
• 1.850 x 183cm = 338.55
• 4.676 × 27 = 126.252

So at this point the equation would look something like this:

• 655.1 + 717.225 + 338.55 - 126.252 = 1585 calories RMR

Now we need to multiply her RMR by her level of activity. In this case, lets say she trains hard 6 days per week and gets about 10,000-11,000 steps per day. In this case, using a 1.725 activity factor would probably be best. 

• 1585 x 1.725 = 2734 calories as her estimated maintenance or total daily energy expenditure (TDEE)

Cunningham Equation

This equation is best if you know an athlete's lean mass. Or, you have their body fat percentage. (Hint: If they don't know what their body fat % is, if they can get a neck, waist, & hip measurement, you can calculate their estimated body fat % by using an online body fat calculator like this one). The data you need to calculate their resting metabolic rate is:

• Age
• Sex
• Body weight
• Body fat % 
• Height 

Just like with the Harris-Benedict Equation, after you have their RMR, which will be reflected in calories, you'll multiply these calories by their activity level to determine their estimated maintenance calorie needs. Remember that activity level includes scheduled training sessions, games/competitions, and their average daily step count. 

• 1.2 = little or no exercise per week
• 1.375 = light exercise/sports 1-3 days/week
• 1.55 = moderate exercise/sports 3-5 days/week
• 1.725 = hard exercise/sports 6-7 days/week
• 1.9 = very hard exercise/sports & physical job or training 2x per day

There are several calculators available online, like this one (just make sure you select the Cunningham in the formula drop down) that make the Cunningham Equation below much easier to calculate:

Men & Women: 500 + (22 x Lean Body Mass [kg]))

Cunningham Equation Example

We'll keep with the same example as we used for the Harris-Benedict, so you can see the difference between the 3 calculations.

• 27-year-old male athlete who's 75kg and is 6'0" (183cm) tall
• Body fat % is estimated at 21% 

Here's how you would calculate their maintenance TDEE using Cunningham:

• 75kg x .21 = 15.75kg of body fat
• 75kg - 15.75kg = 59.25kg lean mass 
• 22 x 59.25kg = 1304
• 500 + 1304 = 1804 calories RMR

Now, we need to multiply her RMR by her level of activity, which, as we know from above, is 1.725.

• 1804 x 1.725 = 3112 calories as her estimated maintenance or total daily energy expenditure (TDEE)

NSCA Estimated Daily Calorie Needs by Activity Level 

If you have the NSCA Essentials of Strength Training and Conditioning 4th edition textbook, head to page 217 to reference Table 10.4. This table is probably the quickest way to estimate an athlete's total daily energy expenditure. You need very little data for this equation, so it's the most basic as well; therefore, is likely to be the most inaccurate. 

Here's what you'll need to calculate it:

• Sex
• Activity Level 

Then, you'll use the following data reference points to calculate their estimated TDEE:

• Men:
  • Men who are lightly active: 38 calories for every 1 kilogram of body weight
  • Men who are moderately active: 41 calories for every 1 kilogram of body weight
  • Men who are heavily active: 50 calories for every 1 kilogram of body weight
• Women:
  • Women who are lightly active: 35 calories for every 1 kilogram of body weight
  • Women who are moderately active: 37 calories for every 1 kilogram of body weight
  • Women who are heavily active: 44 calories for every 1 kilogram of body weight

NSCA Estimated Daily Calorie Needs by Activity Level Example

As we did with the other two examples above, we'll stick with the same 27-year-old, 75kg female who trains 6 days per week and gets about 10,000-11,000 steps per day.

• Female athlete who is moderately to heavily active (you can split ranges as well! - In this example we added 37 + 44 and divided by 2 = 40.5)
  • 40.5 calories x 75kg = 3038 calories as her estimated maintenance or total daily energy expenditure (TDEE)

You might be wondering, how do I know which calculator to use if I have all the data needed to use all 3 of these calculators? If so, our best recommendation is to choose one & try it out. If you give the athlete their targets and you notice that they're losing or gaining on the numbers you've given them, then you'll need to adjust them up or down to see at what level they'll maintain.

Keep in mind, depending on activity level, food intake, and other factors like menstrual cycle in females body weight will vary over the course of a week. So, tracking intake and body weight for at least 2 weeks, with at least 6-8 body weights during this time, can help you dial in where their maintenance range is likely at. 

Need help calculating their protein & carbs now? This blog on protein & carb recommendations for athletes might be helpful to check out. 

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