Sara Pindera
Bachelor of Science in Nutrition and Nutraceuticals. A Canadian with a love of food, fitness and health.

If It Fits Your Macros (IIFYM)

How to calculate your macronutrients

There is a lot of information on the internet about macronutrients and the “If It Fits Your Macros” (IIFYM) diet/lifestyle. You can enter information about your sex, weight, height, ext, into an online macronutrient calculator and it will spit out a number of calories or some macronutrient ratios to follow.

Calculating and following an IIFYM lifestyle may seem like a lot of work, but it doesn’t have to be! Gymaholic introduces you to IIFYM, shows you how to easily calculate your current macronutrients on your own, and change them to suit your goals.

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IIFYM Diet/Lifestyle

The basis of IIFYM is that it doesn’t matter what it is you’re eating, as long as you reach your goal calories and macronutrients for the day. This gives you a type of freedom to eat whatever you want, which can be beneficial to people just starting to get interested in their health and people with advanced knowledge and skills.

The thing that separates a “diet” from a “lifestyle” is long-term stability. Technically you can eat whatever you want, but if all of your calories and macros are coming from fast-food, eventually there will be consequences.

This can be a great starting point for those trying to develop healthier habits, as you can stick with the same amount of calories and macros through the day, but start experimenting by adding in healthier recipes, more fruits and vegetables, fibre and healthy fats.

IIFYM does require some tracking and monitoring, so if it adds too much stress or work to count your macros you may want to try another even simpler method like The 80/20 Rule.

Keep in mind that IIFYM can also lead to some good habits like paying attention and noticing what and how much you’re eating throughout the day. Even if you don’t follow IIFYM, it could be helpful to calculate your calories and macros every once in awhile while working towards a goal.

Calculating Calories and Macros

To decide what your goal calories and macronutrients should be, you first have to find out how much of each you’re eating right now. It’s easiest to find an average, so record roughly how many carbs, protein and fat you eat every day to get an average amount of each. The calculations are really simple, but you’ll still probably have use a calculator to crunch the numbers.

Calories are a measurement of heat released or energy that can be used through the breakdown of the macronutrients: carbohydrates, protein and fat. You don’t have to record calories, because you can calculate them through the macronutrients you record.

Carbohydrates and Protein → 4 calories per gram

Fats → 9 calories per gram

To calculate how many calories you’re getting from carbohydrates or protein, simply multiply the gram amount by 4. To calculate how many calories you’re getting from fat, simply multiply the gram amount by 9. For example, If you eat 150g of carbohydrates, 112g of protein and 50g of fat in a day, your macronutrient calculations would look like this:

150g carbs x 4 calories/g = 600 calories

112g protein x 4 calories/g = 450 calories

50g fat x 9 calories/g = 450 calories

Total Calories = 600 + 450 + 450 = 1500

Macronutrient Ratios

Macronutrient ratios show you the percentage of calories from each of the macronutrients out of your daily 100% calorie total. The example above has a 40/30/30 ratio.

600 calories / 1500 calorie total = 0.4 = 40% calories from carbohydrates

450 calories / 1500 calorie total = 0.3 = 30% calories from protein

450 calories / 1500 calorie total = 0.3 = 30% calories from fats

This information can be used in multiple ways. For example, If you want to increase your total calories to 1800, but keep your ratio the same you can do all of these calculations backwards to find out how many calories would be coming from each of your macronutrients.

1800 x 0.4 = 720 calories from carbohydrates

1800 x 0.3 = 540 calories from protein and fat

720 calories / 4 cal/g = 180g carbohydrates

540 calories / 4 cal/g = 135g protein

540 calories / 9 cal/g = 60g fat

If you wanted to keep the calories the same (1500), but change the ratio to 50/30/20 you get different gram amounts of each macronutrients with the same calorie total.

1500 x 0.5 = 750 calories from carbohydrates (750/4 = 187g carbohydrates)

1500 x 0.3 = 450 calories from protein (450/4 = 112g protein)

1500 x 0.2 = 300 calories from fat (300/9 = 33g fat)


Achieve Your Goals With IIFYM

Just like in the examples above, in order to lose weight, gain weight or maintain your current weight, you can change your calories or change your macronutrient ratio. The most important thing to remember is that everyone is different, so you will likely have to experiment to find the numbers that work for you, however, here are some good starting points.

If your goal is to lose weight, you can decrease your total calories, or reduce the calories from carbohydrates. You can reduce fat too, but fats (especially healthier fats) can be a lot less damaging to the body then excess glucose (simple sugars/carbohydrates) can be.

When reducing your calories you want to start by reducing the total by 5-10%. If you’re consuming 2000 calories, 2000 x 0.1 = 200 calories. After subtracting that 10% or 200 calories, your new total would be 1800 calories.

If you try that 1800 calories for a few weeks and find you aren’t progressing, or you keep that up for a few months and you hit a fat loss plateau, you can either reduce another 5-10% (1800x0.1 = 180, 1800-180= 1620 calories) or you can change your macronutrient ratio.

High Carb - 60/25/15

Moderate Carb - 50/30/20

Low-Moderate Carb - 40/30/30

Low Carb - 25/45/30

If you’re consuming 1800 calories and your ratio of Carbohydrate/Protein/Fat is 50/30/20, you could change that ratio to 40/35/25, 40/30/30 or 40/40/20… It’s best to move slowly, as it would be a bit dramatic to cut 50% carbs down to 30%, but as with before, if you try it for a few weeks or months and decide it’s not working or run into another plateau, you can change the ratio again until you find something that works.

When you’re looking to gain weight you can increase your overall calories by 5-10% or just like in weight loss, adjust your macronutrient ratio to increase the calories coming from protein.


There are so many ways to progress towards and achieve your goals. Calculating your macros and following and IIFYM lifestyle could help you on it’s own, or be a stepping stone to healthier habits. Here are some things to remember:

  • You can eat whatever you want to fill your macros, but being mindful of what you’re eating can make IIFYM a lifestyle rather than a diet.
  • Both carbohydrates and protein have 4 calories per gram, and fat has 9 calories per gram.
  • Calculating your total calories and macronutrient ratios can help you see more clearly what you’re eating now.
  • Changing the total calories by about 5-10% or adjusting your macronutrient ratio can help you towards your goals and push you past a plateau.

Always keep learning and growing. You can do this!

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