Common Nutrition Calculations

While it’s not absolutely necessary to break out the calculator and figure out your ideal daily intake of total calories, and how this number breaks down into carbohydrate, protein, and fat components, it’s worthwhile for serious athletes (and control freaks and nerds, like us).

You can use the method below to determine your daily caloric needs with the caveat that it’s only an estimate because of variables such as lean body mass, fitness level, and metabolism rate. For a more accurate assessment, your caloric needs can be measured through direct or indirect calorimetry in a laboratory.

First we need to calculate your Basal Metabolic Rate (BMR) using your weight, height, and age. BMR calculates the number of calories you need to sustain life if you were totally immobile; i.e., it’s the energy required just to stay alive!

Women: BMR = 655 + (4.35 x weight in pounds) + (4.7 x height in inches) – (4.7 x age in years)
Men: BMR = 66 + (6.23 x weight in pounds) + (12.7 x height in inches) – (6.8 x age in years)

Next we use the Harris-Benedict Formula to multiply your BMR by the appropriate physical activity factor. If you are

  • Sedentary (little or no exercise): BMR x 1.2 = total calories needed per day
  • Lightly active (light exercise/sports 1 to 3 days/week): BMR x 1.375 = total calories needed per day
  • Moderately active (moderate exercise/sports 3 to 5 days/week): BMR x 1.55 = total calories needed per day
  • Very active (hard exercise/sports 6 to 7 days a week): BMR x 1.725 = total calories needed per day
  • Extremely active (very hard exercise/sports and physical job or 2x training): BMR x 1.9 = total calories needed per day

So the question is: Can you get all of the calories you need from plants? Be assured that you can, easily. For example, Chris Carmichael, the famous cycling coach, recommends in his book Food For Fitness that athletes get roughly 65 percent of their caloric intake from carbohydrate, 13 percent from protein, and 22 percent from fat. His numbers are not unique and can be easily met with a plant-based diet.

Sample Calculations and Meal Planning

Let’s take a look at two examples and run through the nutrition calculations we’ve mentioned in this chapter, so you can get an idea of what a typical day of eating on a plant-based diet to meet your specific nutritional needs looks like.

Example: Haley the Half Marathon Hopeful

First, let’s take a woman, 130 pounds, 5 feet, 2 inches tall, 26 years old, who is training for a half marathon and therefore exercising 4 to 5 days per week.

Her Basal Metabolic Rate is:

BMRFemale = 655 + (4.35 x weight in pounds) + (4.7 x height in inches) – (4.7 x age in years)
= 655 + (4.35 x 130) + (4.7 x 62) – (4.7 x 26)

= 1,389.7 calories per day

Because she’s training for a half marathon and running four to five days a week, using the criteria from above we determine that she’s “moderately active,” meaning her activity factor is 1.55. Substituting this value into the Harris-Benedict Equation, we get:

1,389.7 x 1.55 = 2,154.035 calories per day. (Note that this is an average. On heavy training days, she’ll likely eat more to fuel the activity, and on rest or light training days, she’ll naturally eat less than this amount.)

Breaking down her total of approximately 2,150 daily calories into the nutrient ratios we recommend, we get:

Carbohydrate (65 percent): 2,150 x 65 percent = 1,397.5 calories. Because there are 4 calories per gram of carbohydrate, this comes out to 1,397.5  4 = 349.375 (approximately 350) grams of carbohydrate per day.

Protein (13 percent): 2,150 x 13 percent = 279.5 calories. Because there are 4 calories per gram of carbohydrate, this comes out to279.5  4 = 69.875 (approximately 70) grams of protein per day. (Note that this amount of protein falls within the range estimated by the common “0.45 to 0.55 grams per pound of body weight” guideline.

Fat (22 percent): 2150 x 23 percent = 473 calories. Because there are 9 calories per gram of fat, this comes out to 473  9 = 52.556(approximately 53) grams of fat per day.

Example: Frank the 5K First-Timer

Now let’s do the corresponding calculations for a male, 170 pounds, 6 feet tall, age 41, who has decided to get in shape and is training for his first 5K. He’s busy and concerned about injury, so he’s training relatively lightly for just three days each week.

His Basal Metabolic Rate is:

BMRMale = 66 + (6.23 x weight in pounds) + (12.7 x height in inches) – (6.8 x age in years)

= 66 + (6.23 x 170) + (12.7 x 72) – (6.8 x 41)

= 1,760.7 calories per day

Because he’s training lightly for three days a week, from the criteria from above we determine that he’s “lightly active,” meaning his activity factor is 1.375.

Substituting this value into the Harris-Benedict Equation, we get:

1760.7 x 1.375 = 2,420.96 calories per day. (Note that this is an average. On training days, he’ll probably eat slightly more to fuel the activity, and on rest days, he’ll naturally eat less.)

Breaking down his total of approximately 2,420 daily calories into the nutrient ratios we recommend, we get

Carbohydrate (65 percent): 2,420 x 65 percent = 1,573 calories. Because there are 4 calories per gram of carbohydrate, this comes out to 1573  4 = 393.25 (rounded to 393) grams of carbohydrate per day.

Protein (13 percent): 2,420 x 13 percent = 314.6 calories. Because there are 4 calories per gram of carbohydrate, this comes out to 314.6  4 = 78.65 (approximately 79) grams of protein per day. (Note that this amount of protein falls within the range estimated by the common “0.45 to 0.55 grams per pound of body weight” guideline.)

Fat (22 percent): 2,420 x 23 percent = 556.6 calories. Because there are 9 calories per gram of fat, this comes out to 556.6  9 = 61.8444 (roughly 62) grams of fat per day.