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The DAO of calculating macros

In my previous post on the roadmap to intuitive eating, I explained that calorie and macro counting can also be tools in the toolbox of understainding nutrition goals.

In this post, I will explain two of these core methodologies: calories in, calories out (CICO) and If it fits your macros. (IIFYM).


  1. Macros vs. calories vs. portions vs. intuitive eating: What’s the best way to ‘watch what you eat?’ (Precision Nutrition)
  2. Counting macros versus intuitive eating (Jada Blitz fitness)
  3. This is the best macronutrient calculator on the net (Legion Athletics)
  4. IIFYM Diet Guide: Counting Macros for Weight Loss (Legion Athletics)
  5. What is BMR and how do you calculate it for weight loss? (Legion Athletics)

To understand how to get to macros, you ned to understand a few things about calories and macros:

What are calories and macronutrients – and how do they relate?

A calorie is the unit used to measure the energy-producing value of food. Technically, a calorie is defined as the amount of heat necessary to raise the temperature of one gram of water one degree centigrade.

Macronutrients form the major sources of energy in food. They include carbohydrate, and protein, fat, and alcohol. When burned (metabolized), they provide different amounts of energy:

  • Carbs = 4 calories per gram
  • Protein = 4 calories per gram
  • Alcohol = 7 calories per gram
  • Fat = 9 calories per gram

CICO and IIFYM – what are they and what do they have to do with calories and macros>

CICO and IIFYM respectively stand for “Calories in Calories out” and “If it fits your macros.” Applying both of these methods, you can estimate your needed calorie intake for different body composition goals (losing fat, gaining muscle, or maintaining). Based on that, you can toggle the macronutrients that make up that calorie total to derive your desired ration of protein to carbs to fat. You can then use that information to plan your meals, snacks, treats, and even alcohol intake.

Both CICO and IIFYM are premised on some kind of food tracking and measuring (or approximating measuring). While doing this in perpetuity is not sustainable, for some amount of time having this practice can help better judge portion sizes and be able to “ballpark” how many calories and what kind of nutrients are in a particular food.

Research shows that without this training, people are very prone to underreporting their calories consumed and overestimating the amount of calories they are burning. , often by 10 to 20 percent. Fitbits and Apple watches can overestimate calorie burn by over 90 percent. In fact, a 2017 Stanford study found that the most accurate calorie tracker was off by at least 27 percent!

And while food tracking devices like MyFItnessPal and ATE it aren’t perfect (discussed in my DAO of metrics post Part II) at estimating calories consumed, they can at least give you an idea if you are exceeeding an average calorie intake needed by 1000s of calories.

What is CICO?

To understand BMR and its relationship to TDEE, you have to understand the CICO principle. 

The basic energy balance equation is as follows: Calories in = Calories out.

Calories in (CI)  are what you consume in food and drinks.

Calories out (CO) is equal to Total Daily Energy Expenditure (TDEE).

TDEE is a sum of the following:  Basal Metabolic Rate (BMR)+ Thermic Effect of Food (TEF) + Thermic Effect of Activity (TEA)+ Non-exercise Activity Thermogenesis (NEAT). 

Briefly explained, these components mean:

BMR is the biggest influencer of TDEE

The big part of this equation is the Basal Metabolic Rate. Although this is the calories you burn from doing nothing but watching Real Housewives, it is also responsible for the largest portion of your energy output, as seen by the below chart 

Components of total daily energy expenditure (TDEE). BMR = basal metabolic rate; NEAT = non-exercise activity thermogenesis; TEF = thermic effect of food; EAT = exercise activity thermogenesis; REE = resting energy expenditure; NREE = non-resting energy expenditure. Adapted from Maclean et al., 2011.Photo credit: Trexler, Smith-Ryan, Norto, Metabolic Adaptation for Weight Loss: Implications for the Athlete, via Creative Commons, license granting limited permisison for use available here.

How calories and macros are calculated, step by step 

 Step 1:  Calculate your BMR;

 Step 2:  Based on BMR, determine your TDEE (Total Daily Energy Expenditure)

Step 3:  Calculate your target daily calorie intake

Step 4: Calculate your macro needs, starting with protein intake

Step 1: Calculating BMR

Most nutritionists use a formula to determine BMR called the “Mifflin St Jeor” formula, which is generally regarded as more reliable than a formula previously used, the Harris-Benedict formula.(although some professionals still endorse the latter, the overall consenses is that Mifflin St. Jeor addresses the shortcomings of the Harris-Benedict formula). You can plug in your numbers to determine your BMR into one of these calculators:

Step 1 is fairly formulaic, and Step 2-4 is really where the science of your particular bodily needs come in, and where a dietitian’s advice is critical. If weight loss is a goal, a dietitian can help you ascertain why that is and what kind of daily calorie deficit is healthy to achieve that goal. There is a big difference between a healthy calorie deficit of about 10-20 percent that can incur gradual weight loss versus an extreme calorie slashing diet typical of the fad diets we discussed earlier. If weight gain or weight maintenance is a goal, this calorie target is also useful to understand how much intake in the CI side to achieve these objectives.

It’s worth noting that tools for calculating BMR are viewed as very back of the envelope. It’s impossible to ascertain a BMR exactly unless in lab settings. In various studies, scientists have found a significant margin error. The science of the body, especially when it comes to these variables, naturally slants to imperfect. We can never be completely sure about how many calories foods actually contain, either, So think of this as back of the envelope determinations, not exact mathematics. It’s more of a range than a point.

Even if weight loss is not your goal, this is a useful tool stay where you are weight wise but make sure you are getting adequate nutrients to support both your workout regime and your ADLs (activities of daily life). In all three cases, understanding the math the professionals use is useful, but ultimately seeing the professional is the best case scenario. I talk about this in _____

Mifflin St. Jeor Calculation

Below is the Mifflin St. Jeor Calculator, the formula can be located under the calculator. The Mifflin-St Jeor Equation calculates your basal metabolic rate (BMR), and its results are based on an estimated average. Basal metabolic rate is the amount of energy expended per day at rest.

The complete equation varies between men and women, as follows:

Men: (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5

Women: (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161

Here are some sample calculators using Mifflin St. Jeor.

BMR caculator

Mifflin St. Jeor calculator

Legion BMR calculator

Directions for using the calculator:

  1. Select your sex.
  2. Enter in your weight and select lbs or kgs.
  3. Enter in your height and select inches or cm.
  4. Enter in your age. You now have your BMR.

The number you will end up with for your BMR is very close to your healthy body weight times 10.For example, if you are 5’5 and your healthy body weight is 130,  your RMR will be about 1300.

Once you ascertain your BMR, you can assess your total energy expenditure, or TDEE.

Step 2: Calculating TDEE

Most TDEE calculators on the internet use activity multipliers from the Katch-McArdle equation, which  I have also included in the formula steps below.

For calculating the total calorie output, or TDEE, a multiplier is applied based on activity levels.

  • If you rarely exercise, multiply your BMR by 1.2
  • If you exercise on 1 to 3 days per week, multiply your BMR by 1.375
  • If you exercise on 3 to 5 days per week, multiply your BMR by 1.55
  • If you exercise 6 to 7 days per week, multiply your BMR by 1.725
  • If you exercise every day and have a physical job or if you often exercise twice a day, multiply your BMR by 1.9.

Note that some professionals offer different mutipliers. For example, Mike Matthews in his book Thinner Leaner Stronger, a book which I am a fan of asserts that the multipliers in tghe traditional TDEE equation overshoot people’s actual TDEE’s and offers slightly modified multipliers.

You can calculate your TDEE automatically using the TDEE calculator

The best step by step comprehensive BMR/ TDEE calculator I found is by the NASM available here.

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Step 3: Calculate daily caloric intake

Based on your TDEE, whether you want to be in a caloric surplus, deficit or maintenance mode will determine how many calories you will want to aim to consume on a daily basis. This is a decision that should be made with the help of a dietitician or medical profiessional. For info on finding a dietitian, check out my article here.

Step 4: Calculate Macronutrient Ratios

If this is already too overwhelming, you can stop at step 3. In my original DAO of metrics post, we talked about the debate between calorie and macro counting. In all, both are good ways to track food intake and approximate portion sizes. Howver, if the data entry buden of macros is too high, you can stick iwth calorie tracking for now.

What is IIFYM?

“If It Fits Your Macros” (IIFYM) is a dietary strategy that revolves around eating a certain number of calories and amount of protein, fat, and carbs every day from whatever foods you want.

Once you calculate calories, it is possible to determine what your macronutritent needs.

First: Calculate Daily Protein Needs

There is a lot of debate (again) about ideal protein intake needs. According to a lot of “broscience principles” you should be eating 1-1.5 grams of protein pound of bodyweight. But this myth has been debunked. If you actually followed that it would almost be impossible not to get adequate protein needs from natural foods unless you ate large quantities of animal meat at a time, so most people would almost always resort to supplements like powders and bars. The body can only absorb so much protein at a time. The rest gets excreted through the kidneys. That’s not just “expensive urine,” that can be very taxing for the kidneys.

The protein RDA (Recommended Dietary Allowance) for healthy adults is 0.8 g/kg body weight, daily. In a 2009 paper ublished by the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine, the recommendations are between 1.2 and 1.7 grams per kilogram (not pound) for active individuals. So assuming that you have a 5’5 130 lb female that is active, the recommended protein intake would be between 80-100 grams of protein a day. NOT 130-150.

Once you get your protein needs, carbs and fats are “negotiable” based on baseline recommendations and individual goals and attributes.

Second: Calculate Daily Fat Needs

To prevent any fatty acid deficiencies it is recommended to consume at minimum 1g/kg of fat per day. The Dietary Guidelines for Americans also recommends fat should make up 20-35% of one’s total daily calories. Using both of these references you can calculate your daily fat needs:

Third: Calculate Daily Carbohydrate needs

The Dietary Guidelines for Americans recommends that carbohydrates should make up 45-65% of one’s daily calories.

So if you are aiming for 1600 calories, that is about 800 calories from carbs. Which is about 200 g of carbs. 

Takeway : Tools in the toolbox

As a back of the envelope tool, calorie and macro tracking can be useful to “train” you to get an idea of how much food you are taking in and how much you need. They can also be useful meal planning tools. When you establish a regular rhythm of “LBD meals” and understand how much you need to eat around your workouts, you can be more flexible. Look at it like a chef just starting out – in the beginning, they probably have to measure cups and tablespoons but later they intuitively know how much should go in and can eyeball it. You can do the same with your nutrition intake and be more intuitive about what you need.

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