For those unfamiliar with the acronym, I.I.F.Y.M stands for “If it fits your macros”, a phrase coined to describe a particular attitude towards eating and nutrition.

It’s fairly simple, you establish macronutrient numbers that you want to consume in a given day or a given period then, subject to this constraint, you have free reign to consume what you want, when you want.

There are many web based resources that discuss the diet and the idea, at least in its conceptual phase, has been used by bodybuilders for years. We are now seeing it enter the public domain and there are a few websites, such as this one, that claim to be the one-stop-shop resource for the diet.


The good 

There’s a lot that I like about this philosophy. It’s very simple and generally easy to follow, assuming that you have some convenient way to track the macro-nutrients (a smart phone and an app) in the food that you eat.

Put simply, if you “hit your macros” day in day out it is fair to say that, assuming a rational individual who won’t try to consume their protein from black widow venom and their fats from rotting animal carcass then it’s fair to say that you’ll reap most, possibly all of the rewards from your efforts.

Why is it good? It avoids dogma, allows food you enjoy, prevents the formation of unhealthy eating habits, promotes consistency, makes social eating easy and can be adapted for weight loss and gain.

Perfect, right? 

The bad 

There are a few overlooked issues that I don’t like about the concept. In some ways I feel that there have been some grossly simplified ideas for the sake of appearing simple and “easy to use”.

Not created equal

There are the obvious pitfalls that you could, if you were so inclined or perhaps horrendously misinformed, abuse the system with REALLY bad food choices. You could, for example, “hit your macros” by eating at McDonalds for breakfast, lunch and dinner. Maybe not the best attitude to cultivate?

Photo credit GasFan_Canada


With this, its also worth considering that protein is not equal across all sources, you could get all of your protein from grains and collagen if you eat the right combination of foods. That simply isn’t going to cause the same physiological response as an equal quantity from chicken, beef and eggs.

Equally, all fats are not the same. To ensure a favorable hormonal profile its important to get a broad spectrum of fats. Some fats (MCTs and Omega 3) cause a brilliant array of preferable effects in the body, reduce inflammation, promote fat burning, improve brain function and enhance recovery to name but a few. On the flip-side, some fats (omega 6 and man-made trans-fats) cause a damaging tirade of inflammation and metabolic damage.

Unfortunately most tasty foods contain the latter kind. In order to improve your omega 3 to 6 ratio and get enough healthy fats you’re still going to have to preference grass-fed meats, wild caught fish, pastured eggs, untreated oils with a high smoke point and fish oils. Not quite the pizza-fest most people envision when their told their macros are the only constraint.

Carbohydrates are less problematic, fructose would be to obvious choice to demonize and I would never advocate this comprising all or most of your intake (again, its prevalent in highly processed foods) however, some fruit and small amounts of fructose aren’t a problem. Some may reference the issue of complex and simple carbs and the GI index. Without delving into an issue that actually gets fairly complex, it doesn’t matter. In fact, I would advise simple carbs OVER complex ones. Both cause an insulin response but the more “sugary” your choice, the sooner insulin returns to baseline and the sooner you can resume burning endogenous fat stores.


Timing matters 

People like breakfast, no question about it. Most wake from their slumber in a hunger induced stupor and throw down all sorts of syrup soaked pastry or mounds of cereal to stifle the rumble before beginning their day.

For fat-loss, breakfast is terrible – as bad as it gets. 

The intermittent fasting movement Kiefer’s Carb-Backloading protocol has helped to raise awareness of the negative sides of breakfast.

It doesn’t kick-start your metabolism, it isn’t absolutely needed to stop catabolism – it stabs your fat-loss……in the back. In order to burn the most fat possible, the first few hours of the day should be left calorie-free.

However, like I said, people like breakfast and left to their own devices, they’ll eat it. Now they’ve got arbitrary constraints in the form of macros. A couple of croissants with Jam at 7:00am? Sure why not, I’ll eat my protein later. Bye bye progress.

I’m going to concede that what you eat may not be the be all and end all of fat loss (assuming you follow IIFYM) but WHEN you eat does. Without additional constraints you could throw away your allotment of one macro or maybe all three in the first hour of two of waking – good luck with the rest of the day. Equally, protein should be eaten post and pre workout and carbs will always be partitioned better post-workout in the absense of fats.


The Propane way 

IIFYM is great in the sense that its easy to follow but it needs more structure to work well, at least in the long term.

The solution?

That’s easy…..

The Next Step

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4 responses to “A closer look at I.I.F.Y.M

  1. Plenty of people get in contest condition and eat carbs at breakfast.
    Nice article, neatly summarised the pros and cons of IIFYM. I really need to get round to ordering some omega 3 caps, don’t think many students can afford grass fed beef!

    “For me life is continuously being hungry. The meaning of life is not simply to exist, to survive, but to move ahead, to go up, to achieve, to conquer” – Arnold Schwarzenegger

    “the ones wanting to be ‘toned’ still have bodybuilding goals, they just don’t realise it” – Yusef

  2. I like to keep it really simple… Minimum 80% calories from high quality protein, minimally refined carbs and healthy fats, and the rest from whatever you want. The key is to accurately track things. If you aren’t ACTUALLY tracking your macros then forget about it as you’ll easily overshoot.

    IIFYM is a great way to get into awesome shape and still enjoy your diet. Gone are the days of 24/7 chicken breast, brown rice and broccoli.

    1. Agreed on the 6-8 meals of chicken breast and broccoli. 80% is playing it very safe, you could in theory have what you wanted provided it fit with the macros, but as you said it becomes more and more easy to overshoot with the poorer quality food choices.

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