Macro Dieting (IIFYM) Diet Guide: Analyzing Customized Macronutrient Intake

Does IIFYM actually work? Or is it more complicated than that?

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If you have spent much time around bodybuilders, CrossFit athletes, or other serious weight lifters, you might have heard these strength athletes discussing macros and macro ratios and Macro Dieting (IIFYM) diet.

Macros refer to the three major macronutrients: carbohydrates, proteins, and fats.

Macro dieting, also known as IIFYM dieting, is an approach to diet and nutrition that puts structure or restrictions on the macronutrients rather than total calories.

In this guide, we will discuss what the Macro Dieting (IIFYM) diet plan involves, the principles behind the IIFYM diet meal plan, foods to eat and avoid, and potential IIFYM diet benefits and drawbacks.

We will cover: 

Let’s get started!

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What Is Macro Dieting (IIFYM) Diet?

The IIFYM diet stands for the “If it fits your macros” diet. 

The Macro Dieting (IIFYM diet) is also called the macro diet, macro dieting, a macro ratio diet, or a macro split diet. 

In the IIFYM dieting approach, rather than putting restrictions on the total number of calories you can eat per day, you focus on either reaching a certain target intake for one or multiple macronutrients or you limit one or more macronutrients.

The macronutrients refer to proteins, fats, and carbohydrates. 

Note that alcohol is sometimes classified under the macronutrients because it provides calories, but it is not part of the Macro Dieting (IIFYM) diet plan since alcohol should not constitute an appreciable percentage of your caloric intake when your goal is optimizing health.

Some people find that macro dieting is more flexible dieting and supportive of different nutritional and caloric needs than regular weight loss dieting.

To that end, while some people do follow a macro diet or macro ratio dieting approach for fat loss, the IIFYM diet is not inherently a weight loss diet or approach to weight loss. 

It is often actually used for building muscle mass, or in a bulking/cutting cycle for bodybuilders.

Fitness enthusiast Anthony Collova created the IIFYM diet because he wanted to design an approach to dieting that better met the needs of athletes and had some more flexibility.

Although the IIFYM diet was initially designed for athletes, it is now used by everyday individuals, including those looking to lose weight, gain weight, or improve their health, regardless of whether they are particularly physically active.

A plate with different types of food like beef, eggs and broccoli.

How Do You Follow Macro Dieting (IIFYM) Diet

As mentioned, instead of tracking calories, the IIFYM diet plan tracks three of the four major macronutrients.

The three macronutrients that constitute an IIFYM diet meal plan include the following:

Macro Dieting (IIFYM) diet:

  • Grams of Carbohydrates: Carbohydrates contain 4 cal per gram and include foods such as fruits, vegetables, whole grains, sugars, etc.
  • Grams of Protein: Proteins contain four net calories per gram and are found in foods such as meat, poultry, fish, eggs, seafood, tofu, dairy, etc. 
  • Grams of Fats: Fats provide 9 cal per gram and are found in oils, nuts, seeds, butter, avocado, etc. 

Note that alcohol provides seven calories per gram, but it’s not part of the structure of an IIFYM diet plan.

Also, most foods provide a mix of multiple macronutrients.

The above examples are just a few food groups that are rich in a particular macronutrient but may or may not contain one or both of the other three major macronutrients.

Aside from having the unifying theme that you are tracking your macros in a macro diet, macro dieting is quite flexible.

How do you calculate your macros for the IIFYM diet, and how do you determine your daily macro requirements for the IIFYM diet?

There isn’t a set target for any or all of the macronutrients that will apply to everyone doing an IIFYM diet program.

For example, you might be following an IIFYM diet weight loss plan in which you try to have a high protein, low carb diet.

A table full of high protein foods like nuts and salmon.

In this instance, you might set your protein intake to be the maximum recommended protein intake per day of about 2.2 g per kilogram of body weight or 1 g of protein per pound of body weight per day.

Then, you would calculate how many calories this would work out to be.

From there, you would set your fat and carbohydrate percentages.

On the other hand, the IIFYM diet for runners and endurance athletes might prioritize carbohydrates, seeking to obtain perhaps 65% of the total caloric intake from carbs per day to support endurance training.

Then, the athlete would look at the remaining 35% and split that between fats and proteins as desired.

He or she might aim to do 20% of the remaining calories from proteins and 15% from fat, which would be a relatively low-fat but high-carb diet plan. 

What is the macro ratio for IIFYM?

The takeaway is that there isn’t one specific IIFYM diet macro split that everyone will use; rather, IIFYM dieting is an approach to structuring your meal plan based on your target macro goals.

Thus, to do macro dieting, you would follow these steps:

  1. Decide on your macros in terms of the ratio that you want.
  2. Weigh and measure all of your food.
  3. Track your macros in your IIFYM diet meal plan to stick within your macro ratio targets.

Note that the official Macro Dieting (IIFYM) diet plan does have specific target macro ranges.

There is even an IIFYM macro calculator to help you determine your macros.

Here are the basic steps for how the IIFYM diet recommends setting up your macro dieting splits:

How To:

  1. Calculate your (basal metabolic rate) BMR and then your total daily energy expenditure (TDEE) by accounting for your activity level and exercise. You can calculate your TDEE here.
  2. Adjust your caloric needs based on your weight goals. According to the IIFYM diet weight loss and IIFYM diet gain recommendations, you should decrease your calculated TDEE by 15 to 25% if you want to lose weight and increase your calculated TDE by 5 to 10% if you want to gain weight or build mass.
  3. Calculate your macros by multiplying your body weight by 0.7-1.0 protein and 0.25-0.4 for fat, and then use the remaining for carbohydrates. The recommendation is to go higher in the protein range for weight loss and higher in the carbohydrates (so lower in protein and fat) for weight gain.
  4. Make sure that 20-25% of your lean body weight (in pounds) of your grams of carbs per day is dietary fiber.
  5. Calculate the calories of each macro based on your weight goals and macros.
A piece of paper with nutrition plan written on it.

What Can You Eat On the IIFYM Meal Plan?

There are no specific restrictions in terms of what you cannot eat on the Macro Dieting (IIFYM) diet plan.

However, when the goal is to improve health or follow the IIFYM diet for weight loss, you should focus on whole, natural, unprocessed foods that fit within your macros.

Examples include fresh vegetables, fruits, whole grains, nuts, seeds, eggs, lean proteins, and healthy fats such as avocado and olive oil.

Limit processed foods, refined grains, fried foods, industrial oils, processed meats, alcohol, sweetened beverages, and foods with added sugars.

You will need to use a food tracking app to keep track of your macros.

Is the IIFYM Diet Good for Weight Loss and Health?

Overall, the IIFYM diet can be good for weight loss, weight gain, and overall health if you choose nutritious foods and settle on a healthy macro ratio diet for your IIFYM plan. B

y tracking your macros, you may consume fewer calories, which could result in a calorie deficit, you may experience weight loss.

Indeed, studies1Camacho, S., & Ruppel, A. (2017). Is the calorie concept a real solution to the obesity epidemic? Global Health Action10(1), 1289650. found the IIFYM diet can work for weight loss, particularly if you are following an IIFYM diet plan that is high in protein2Aller, E. E. J. G., Larsen, T. M., Claus, H., Lindroos, A. K., Kafatos, A., Pfeiffer, A., Martinez, J. A., Handjieva-Darlenska, T., Kunesova, M., Stender, S., Saris, W. H. M., Astrup, A., & van Baak, M. A. (2014). Weight loss maintenance in overweight subjects on ad libitum diets with high or low protein content and glycemic index: the DIOGENES trial 12-month results. International Journal of Obesity38(12), 1511–1517., fiber, and whole, natural, satiating food.

A table of food made up of meat, cheese, carbohydrates and fruit.

However, caloric balance3Howell, S., & Kones, R. (2017). “Calories in, calories out” and macronutrient intake: the hope, hype, and science of calories. American Journal of Physiology-Endocrinology and Metabolism313(5), E608–E612. more than macro ratios.

Studies also suggest that food tracking4Mateo, G. F., Granado-Font, E., Ferré-Grau, C., & Montaña-Carreras, X. (2015). Mobile Phone Apps to Promote Weight Loss and Increase Physical Activity: A Systematic Review and Meta-Analysis. Journal of Medical Internet Research17(11), e253. help support weight loss, and not having restricted foods may increase adherence.

However, the IIFYM meal plan can be difficult to set up properly and may require assistance from a nutritionist or registered dietitian.

Additionally, it can be time-consuming and cumbersome to track all of your macros unless you find an IIFYM diet meal plan that you follow quite consistently so you don’t have to track daily once you get into a routine.

Some people also find that tracking food may trigger disordered eating.

Finally, one other downside to the macro dieting approach is that it doesn’t dictate the foods that you eat.

This can lead to deficiencies in micronutrients and/or doesn’t necessarily mean that you will make healthy food choices if it fits your macros. In other words, there isn’t a hierarchy put in place of nutrient-dense foods.

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Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a NASM-Certified Nutrition Coach and UESCA-certified running, endurance nutrition, and triathlon coach. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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