IIFYM (If It Fits Your Macros) – Ultimate Guide To Flexible Dieting

If you are active in any of the online fitness communities, you’ve probably heard of people talking about “If It Fits Your Macros (IIFYM)” or “Flexible Dieting” before. The chance is big that the conversations brought up Pop Tarts and that eating junk food while getting leaner was part of the discussion. But is that the philosophy behind IIFYM? An excuse to eat junk food, Pop Tarts and ice cream every single day?

Let’s find out.

How Does “If It Fits Your Macros” Work?

IIFYM or Flexible Dieting is relatively “new” as a popular dieting ideology in the fitness world, but bodybuilders have actually been doing it for a long time already.

IIFYM is a way of dieting that focusses on meeting daily macronutrient intake targets, and not what you eat to get there. 

What is a “macronutrient”?

A macronutrient is any of the nutritional components of the diet that are required in relatively large amounts. There are three macronutrients required by humans: carbohydrates, lipids (fats), and proteins. Each of these macronutrients provides energy in the form of calories. For example:

  • In carbohydrates, there are 4 calories per gram
  • In proteins, there are 4 calories per gram
  • And in lipids (fats), there are 9 calories per gram

This means that if you look at a food label and it lists 10 grams of carbohydrates, 0 grams of protein, and 0 grams of fat, that food would contain 40 calories.

You plan your daily meals to provide you with a certain amount of protein, carbohydrates and fat, based on your goal (losing fat or building muscle). It’s actually a form of calorie counting, since your macro’s will fill out a certain amount of calories you want to take in per day.

For example, if I want to gain weight I usually eat 3500 calories per day. These 3500 calories consist of 180 protein, 90 fats and 492 carbs.

Now here is the interesting part about IIFYM that people can’t really believe at first:

As long as I hit those “macro” targets every day, the foods I eat to reach those targets with not negatively affect my body composition.

My protein could either come from plain tilapia or from fatty ground beef, my carbs from brown rice or candy and my fats from coconut oil or chocolate. As long as I hit the macro’s for the day, I will lose fat or build muscle depending on my goal.


500 calories, 40g protein, 40g carbohydrates and 20g fats derived from tilapia, brown rice and olive oil.

Is equal to:

500 calories, 40g protein, 40g carbohydrates and 20g fats derived from a peperoni pizza!

I know this sounds ridiculous and unreal at first, but hear me out..

Is The “If It Fits Your Macros” Diet Effective?


The answer is yes, it is absolutely effective, if you apply the principles correctly. Let me explain how it works.

Your body burns a certain amount of energy every single day, and this is measured in calories.

A calorie is the amount of energy required to heat up one kilogram of water one degree Celsius.

Now, to be able to lose fat, you need to fuel your body with less energy than it burns. When you do this, your body has to get the energy it needs from somewhere else, so it will get it from its fat stores.

When we’re talking strictly weight loss (not necessarily fat loss), a calorie is a calorie, REGARDLESS of where it comes from.

This is why you could eat nothing but French Fries and Ice Cream every day and lose weight as long as you fuel your body with less energy than it burns.

Don’t believe me? John Cisna lost 60 pounds in 3 months by only eating McDonalds every day.

The point is clear. So why is it called If It Fits Your Macros and not If It Fits Your Calories?

When we’re talking strictly weight loss, a calorie is a calorie. When we’re talking body composition, there is more to the story..

If you want to lose weight while maintaining as much lean muscle mass as possible, you have to do more than just being in a caloric deficit.

  • You need to get enough protein per day to preserve muscle mass
  • You need to get a certain amount of healthy fats per day, which play an important role in hormone synthesis.
  • You need to ensure you eat enough carbs to provide your muscles with glycogen stores to maintain workout intensity

That’s why counting macros is far superior to just counting calories. It enables you to focus on improving your body composition, not just dropping or gaining pounds that include a percentage of muscle.

Now, what you eat in order to hit those macronutrient targets is of secondary importance when we’re talking about body composition.

The reality is that the carbs from fries will be turned into glucose and glycogen just like the carbs in brown rice. The protein in a fat burger is made up of same amino acids as a plain chicken breast.

With that said, it isn’t a smart idea to get all your carbs from fries and protein from fatty burgers. Which brings me to my next point..

Eat Junkfood And Get Shredded? It’s Stupid.


So like I said, you could actually eat McDonalds or Pop Tarts every day and lose weight, but this doesn’t mean that you should.

You have to understand that food is more than just sources of protein, fats and carbs. It is also our source of micronutrients (vitamins and minerals).

A problem with candy and other overly processed foods and fast foods is that they are lacking in micronutrients. A great benefit of eating “clean” is that is provides your body with a lot of micronutrients.

If you eat too much junk food and processed foods and too little nutritious foods, you can actually develop vitamin and mineral deficiencies that can cause different type of health problems.

Next to that;

  • Consuming increased amounts of high-glycemic index carbohydrates are associated with increased risk for chronic disease.
  • Too much low-quality processed meat may increase risk of cancer
  • Trans Fats (found in many processed and junk foods) will increase the risk of heart disease, diabetes, infertility and more.

Health is always more important than how you look. That’s why you want to eat those foods in moderation, and not include them for the majority of your diet.

You could eat all this stuff the whole day and still get shredded. But does being shredded really matter if your hormone profile and immune system are messed up and if your body is starving for nutrients? Health is always more important.

So How Should You Use IIFYM ? pizza iifym

I apply the following principles to my diet and those of my clients;

– 80% of your daily calories should be from healthy (micronutrient-dense) foods.
– LIMIT the amount of trans fats you eat.
– You should consume 10-13 grams of fiber per 1000 calories.
– Meal timing does not matter. You can eat either 8 times a day or 3 times a day. As long as you hit your set macro and caloric targets, you are fine.

One of the biggest problem people face when dieting is that they get to a point where they just can’t eat chicken and steamed veggies no longer and one bite of something sweet leads to a full binge.

The best way to avoid this is to simply eat healthy foods that you like on a daily and include some treats when you feel like it. For example, if you rather have some ground beef than chicken, work it into your macros. If you would rather have some pasta instead of oatmeal, work that into your macros. If you are really hungry, fit in some extra calories for a big meal and cut out some calories from the next one. Simple as that!

As long as the majority of your daily calories come from healthy, micronutrient dense foods, feel free to include some treats.

For example, if you love Ben & Jerry’s ice cream, work some in for the night. If you’ve been craving pizza for a week, make room for a few slices.

This is the way to get results. I usually eat about 90% clean foods. One day I’ll have some ice cream, the next day some chocolate. I switch it up.

Bottom Line Of IIFYM

I’m not saying that you should go out right now and get you a box of Pop Tarts and a can of coke just because it fits your daily macros. Your diet should still be based around healthy nutritious foods. However, if you’ve been craving ice cream or a donut and it fits your daily macros, then go ahead and have you some. It won’t affect your body composition, food choices are irrelevant. Meeting daily macros and caloric requirements will give you results.

IIFYM is not a diet and not a lifestyle. It is a philosophy that can make your life easier. It’s actually just a method of counting calories without looking at food sources but strictly at macros and calories.

IIFYM does not mean you can eat however much you want of whatever you want. It means you can eat like a regular human from time to time. Use common sense and base your diet mostly around healthy foods to ensure you have a micronutrient intake such as fiber, minerals vitamins and omega’s.

Remember that your long-term health depends on more than just macronutrient intake.

Next to that, just enjoy yourself in moderation while seeing the results that you want.

Comments (8)

  1. Kane says:

    Detailed and easy to folow! Watched your video as well. I really like this approach to diet, trying it out atm and love it so far. Thanks mate!

    1. Student Aesthetics says:

      Thank you!! Appreciate it. Glad it works great for you 🙂

  2. Vinny says:

    Might need to do this around Wednesday, incorporate peanut butter or something for a “dessert” since Ill be trying the refeed on sunday, just to make me feel like I don’t want to binge as much….

    1. studentaesthetics says:

      Sounds good!

  3. Jorge Silva says:

    Been doing IIFYM, liking it so far. The only thing that keeps grinding my gears is the reliability of the macros I input for unlabeled foods (chicken breast, turkey breast, Steak, …). Anyone can provide a good source?

    1. Student Aesthetics says:

      If you buy it at a butcher it’s always going to be a little hard. In grocery stores they have labels of all the food! You could compare with those 😉

  4. Toni says:

    I love love LOVE this. I’m trying to drop a few pounds while making sure I’m doing it properly and keeping my body well fed while I’m doing so. I have found that combining this approach with a few good rounds of some kind of cardio at least four times a week(strength training to come when my messed up shoulder quits bothering me)has already got me a good eight pounds lower than when I began just after the middle of March. Slow, steady healthy weight loss while being able to have the occasional burger, or pizza, or pasta….I’m not a huge complex carb fan, but once in awhile is nice. I can ever still have a beer or glass of wine or two. I’m not suffering or feeling as though I’m missing out in any way, and figuring out the best sources to get my macros from is pretty cool too.

    1. Student Aesthetics says:

      Right on!! Way to go

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