Calculate Your Macros in 4 Easy Steps
Dec 06, 2021
How to Calculate Your Macros
Calculating your macros is an exact science. We use the Harris-Benedict equation backed by long-term, scientific evidence. Below is the step-by-step guide.
Step 1 Calculate Your BMR
Your basal metabolic rate (BMR) is the rate at which you burn calories (energy). To calculate this, we use the Harris-Benedict question as below.
MEN = 66+(6.2 x weight (lbs)) + (12.7 x height (in)) – (6.76 x age (years))
WOMEN = 655.1 + (4.35 x weight (lbs)) + (4.7 x height (in)) – (4.7 x age (yeas))
But why different values for MEN and WOMEN? Well, in general women are much more efficient at burning carbohydrates than men, therefore on average require fewer Carbs, calories when standardizing for the same height, weight, and age. It is to this point that the sexes have variable height, weight, and age multipliers.
Example
A man and women come to see for BMR calculation. They are both 36 years old, 5’9”, and 180 lbs.
Man’s BMR = 66+(6.2 x 180) + (12.7 x 69) – (6.76 x 36) = 1814.9 kCal/day
Woman’s BMR = 655.1+(4.35 x 180) + (4.7 x 69) – (4.7 x 36) = 1593.2 kCal/day
See the difference. The women at the same height, weight, and age require fewer Calories, most likely due to the high efficiency at which she burns Carbs, thus lower demand.
Step 2 BMR X Activity = Total Calories
Your activity is also an important part of your caloric needs. If you are sitting on the couch writing a blog post, instead of being at the gym, your BMR will be different on that day, averaging over a week. The next step is to account for these activity differences.
To do this, take your BMR and multiply it by your activity level to obtain your total kCal/day
BMR x 1.200 = 0 days/week
BMR x 1.375 = 1-3 days/week
BMR x 1.550 = 3-5 days/week
BMR x 1.725 = 6-7 days/week
BMR x 1.900 = heavy workouts or twice/day
Step 3 Activity Type or Body Type
What are your goals? Do you want to gain muscle? Loose fat? Are you someone with a larger bone structure who wants to improve your overall composition? Introspect and determine your goal or body type and use the below macro compositions to reach these goals. Note the largest difference tends to be firstly in the Carbohydrate percentage, which is then budgeted toward your other Macros. Then take your total calories (above) and multiply by the percentage of macros needed for each composition (ie. 40% = 0.4).
Goal-Directed
Bodybuilding or Muscle Gaining
40-60% Carbs, 25-35% Protein, 15-25% Fat
Maintenance
30-50% Carbs, 25-35% Protein, 25-35% Fat
Fat Loss
10-30% Carbs, 40-50% Protein, 30-40% Fat
Body Type
Ectomorphs – naturally thin people
50-60% Carbs, 20-30% Protein, 15-25% Fat
Mesomorphs – naturally muscular people
35-45% Carbs, 25-35% Protein, 25-35% Fat
Endomorphs – high body fat or bone structure, pear-shaped
20-30% Carbs, 30-40% Protein, 35-45% Fat
Step 4 Convert Macro Calories to Grams
Next, we have to determine the actual amount of food you require in each macro category, defined in grams (NOT Grahams). This will help you to determine the amount of each macro needed by weight and volume through measuring (via a scale or measuring implement).
To do this, take the calories.
Carbs = 4 kCal/gram
Protein = 4 kCal/gram
Fat = 9 kCal/gram
Take your total from STEP 2 and multiply by your percentages (ex 40% = 0.4)
TOTAL x %Carb = Carb Calories
TOTAL x %Protein = Protein Calories
TOTAL x %Fat = Fat Calories
Then, take these values and divide the calories by the number of kCal/gram for each nutrient.
TOTAL x %Carb = Carb Calories/4 kCal/gram = Grams of Carb
TOTAL x %Protein = Protein Calories/4 kCal/gram = Grams of Protein
TOTAL x %Fat = Fat Calories/9 kCal/gram = Grams of Fat
Let’s Walk Through An Example
A 5’9’’ (69 in) 180 lb 36-year-old man who works out 3-5 times a week and wants to lose fat
STEP 1
Calculate the person’s basal metabolic rate (BMR) using the above equation
BMR = 66+(6.2 x 180) + (12.7 x 69) – (6.76 x 36) = 1814.9
STEP 2
As he works out 3-5 times weekly, select the BMR activity modifier and multiply the BMR by 1.550 to obtain the total calories
BMR x 1.200 = 0 days/week
BMR x 1.375 = 1-3 days/week
BMR x 1.550 = 3-5 days/week
BMR x 1.725 = 6-7 days/week
BMR x 1.900 = heavy work outs or twice/day
Total calories 2813
STEP 3
Calculate your macro calories given that fat loss if the goal (20% Carbs, 45% Protein, 35% Fat)
Carbs = 2813 x 0.2 = 563 kCal
Protein = 2813 x 0.45 = 1266 kCal
Fat = 2813 x 0.35 = 985 kCal
STEP 4
Calculate your macro grams by diving by the number of kCal/gram for each macro (ie. 4 kCal/gram for Carbs and Protein, 9 kCal/gram for Fat).
Carbs = 563 kCal/4 = 141 grams/day
Protein = 1266 kCal/4 = 316 grams/day
Fat = 985 kCal/9 = 109 grams/day
