Diet if it fits your macros (IIFYM)

Published on May 22nd, 2013 | by George Conte


How to do If It Fits Your Macros (IIFYM) like a pro

If it fits your macros (IIFYM) is a diet approach that was created by people participating in exercise and weight loss online communities. The main focus of this diet system is to decrease the stress by the usual diet restrictions most people face when following a low calorie nutritional plan.

This nutritional approach best suits people that exercise regularly with anaerobic methods like weight lifting and aerobic methods like running or swimming. This is important because such people need specific amounts of protein, fats and carbs daily in order to maximize muscle gaining when on high calorie intake or minimize muscle loss when on low calorie intake.

Of course IIFYM is also appropriate for people that don’t exercise at all and just want the benefits of a “less strict” diet system that actually works at burning fat.

How does IIFYM work?

People following this diet plan simply calculate their daily macronutrient needs and then they are free to eat what they want based on that principle. If you need 100 grams of proteins, 200 grams of carbohydrates and 80 grams of fat per day then you just eat whatever you want based on these quantities.

A basic frame to follow when you calculate you macronutrient needs is:

  1. Calculate your basal metabolic rate (BMR) and then your total daily energy needs (TDEE)
  2. Calculate your protein, carbohydrate and fat needs. This can be usually done by consuming 1 gram of protein per pound of your weight, 0,5 grams of fat per pound of weight and the rest go on carbohydrates. You can find more info on how to do all these calculations here. If you need a more scientific approach on what are the minimum amounts of macronutrients you have to consume daily just follow this guide here about DRIs and RDAs.
  3. Create your favorite daily meals based on the values you just figured that are appropriate for you. If you need more help on the best sources (and what amounts of calories and macronutrients they contain) of protein, carbohydrates and fat click on these links: best sources of protein, best sources of carbohydrates and best sources of fat.

An example of an IIFYM nutritional plan

Let’s say I weigh 160 pounds and I want to lift weights 3 times per week and do aerobic exercise 2 times per week. If you don’t want to do the math by hand you can use the online calculators from or

Based on the frame above:

  1. I will calculate my BMR: that is 1941 calories per day. I will then calculate my total daily energy needs (TDEE) that are: 2871 calories per day.
  2. I will calculate my daily macronutrient needs that are for protein:  1 gram X 160 pounds = 160 grams of protein. For fat 0,5 grams X 160 = 80 grams of fat per day and the rest can be carbohydrates and anything else we want. Remember these calculations are for a person that will exercise anaerobicaly. If you don’t want to do any weight lifting and still want to follow IIFYM just consume less proteins like 0,5 grams per pound of your weight, fat remains the same. Ok so far I need to consume 160 grams of protein X 4 calories = 640 calories from protein. 80 grams of fat X 9 calories = 720 calories from fat. Total of 640+720= 1360. My TDEE is 2871 – 1360 = 1511 calories remain that I can consume from carbs or whatever I like (more fat or protein). If I decide all of the rest of my calories to come from carbs then 1511/4 =  377 grams of carbs. So I can now consume daily based on IIFYM: 160 grams of protein, 377 grams of carbs and 80 grams of fat.
  3. My favorite sources of proteins are chicken, calf and fish like salmon and tuna. I can eat about 800 grams of lean chicken breast or tuna per day for my protein needs. Some of my favorite sources of carbs are fruits, vegetables, rice and whole-wheat pasta. Finally my favorite fat sources are olive oil and nuts. Depending on the meals I want to create I will calculate separately my macronutrients. For example if I eat 4 moderate meals per day I will divide 2871/4= 717 calories per meal that come from 160/4= 40 grams of protein, 377/4=94 grams of carbs and 80/4=20 grams of fat. So a typical 717 calorie meal would look like 200 grams of lean chicken breast with 120 grams of brown rice and a small vegetable salad with 15-20 grams of olive oil. Of course the beauty of IIFYM is that you can eat whatever you want at some of your meals and then adapt your rest meals to your macronutrient needs. So you could start with a big 1000+ calorie meal and then do smaller meals though the day. You could also do the opposite if you are going out at a night party you could eat smaller meals and then eat more at night. This is why IIFYM is also called flexible dieting.

Benefits of IIFYM

  • You can eat what you want when on social situations like parties, restaurants etc. and not feel socially awkward or isolated.
  • Less psychological pressure to follow a low calorie nutritional plan.
  • Higher chance of actually succeeding with this diet plan since it applies less pressure to you.
  • Calculating and monitoring your daily intake in macronutrients helps you to stick to a diet more and more realistic about your true calorie intake. This will help you fight excuses like the “slow metabolism myth” that can only set you back in your life.

Negatives of IIFM

  • Some people use this system as an excuse to eat unhealthy foods. Yes you may still succeed on losing weigh while eating saturated or trans fats and high glycemic index carbs from junk food but your health with deteriorate.
  • You still need to calculate what your daily meals include in macronutrients.
  • Some people completely forget that along with macronutrients you also need appropriate quantities of micronutrients like vitamins and minerals. This is why it is important to take vitamin supplements under this diet plan.


IIFYM is a great system to successfully meet your goals and lose weight while you face less diet restrictions. Don’t forget that IIFYM is not an excuse to go rampage and eat junk food. You still need to consume appropriate foods like whole-wheat carbs and good fats like monounsaturated and omega-3 if you want to remain healthy. As long as you follow the IIFYM principles and at the same time your macronutrient sources are clean you will lose weight and be healthy at the same time!

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About the Author

George Conte is a student of Nutrition and Dietetics, a fitness and healthy living enthusiast. After seven years of personal experience with weight loss, exercise and a total body transformation where he managed to burn 121+ pounds of fat he became the founder of A website dedicated to help you overcome obesity and transform your life the same way he did!

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