Usually, IIFYM is discussed from the standpoint of:

“is this approach optimal for health, fat-loss or muscle gain?”,

“Is the nutritional profile of this diet, when taken to extremes, too deficient in essential nutrients?”

“..but is dirty food REALLY OK?”

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Well, I’m here today to say that, actually, none of these arguments really matter and I’m going to try to explain, using some economic theory and plane old logic, why that is.

First, an assumption:

We have to assume you’re rational. As a person interacting with in the world, your goal on a daily basis is to maximise your utility subject to the various constraints you are either subject to, or impose on ourselves.

Utility is just a proxy for happiness, contentment, and no matter what your goals, you’re in the pursuit of happiness whether consciously or not. So, everyone’s happiness (utility) is determined by different things. Some factors contribute negatively (bills, work, stress etc) and some positively (friendship, money , sex etc). Most of your daily actions will serve to preferentially influence this function, namely, seek out as much money, sex and friendship (for example) as possible, while equally minimising stress, work and bills.

By way of example:
You’re reading this website so you can increase your understanding of training, nutrition and everything that goes with it . This is because either, learning increases your utility, or you feel that by improving the way you look and perform, you’ll be more attractive, confident, have more friends, be happier etc., etc.

This extends to everything from the clothes you wear to the job you do. However, these choices are always subject to limits and constraints – often time, money and perceived effort.

So a Ferrari would likely cause greater utility than a Honda but, due to financial constraints, you pick the car you most prefer, subject to what you can afford to spend.

So, you’re a rational person making daily decisions such that your utility is as high as it possibly could be subject to limits.

Now, I imagine your thinking, how on earth does this apply to the question can I have poptarts for breakfast brah”?


Well, the caveat is that we have to assume, as a baseline, that we always want to be as happy as we possibly can be, subject to the limits we create or are imposed on us. But, with regards to IIFYM, let me start at the beginning:

Let’s consider, for the sake of discussion, what is the best diet for fat loss?
We’re just using anecdotal evidence here but I’m sure you can agree with the following conjectures:

There are examples showing that low carb works -> both Yusef, Jonny and their clients and many others have had success with carb night and other low carb diets. Here’s the physiology.

However, there are also examples that high carb works -> again, Yusef, Jonny and many others got very lean eating haribo and marshmallows

There are examples that a high/regular meal frequency works -> at least 50% of modern day bodybuilders natural and otherwise

However, there are also examples that IF works -> Berkhan et al

So, contradicting concepts, all of which still succeed in fat-loss, what does this tell us? Well, it simply explains that no single one of these factors individually explains fat-loss. However, there is a commonality in all of the above situations. All involve calorie and macro-nutrient manipulation.

In other words, the number one factor to respect is calorie balance. That’s not to say that optimal body composition is quite as simple as calories is versus calories out, it isn’t. But, eat in excess of requirements and you’ll gain weight and vice versa. This is basic, irrefutable physics.

From this, we can say with reasonable certainty that the minimum implementation required to ensure fat-loss is to restrict calories. While meal frequency, carbs etc may pose some significance, they are not the primary determinant.

Because most reading this are concerned more with body composition than weight we must sacrifice simplicity to an extent. Body composition is always best with the greatest ratio of muscle to fat, this holds true if you want to be a mens health cover model or just look good in a bikini – both require decent levels of muscle mass with minimal fat.

So, from this, if weight loss/gain is governed by calorie balance, the other element we should consider is muscle mass gain and retention. What are the main factors here? Well, looking at the research, the two main drivers are:
1) sufficient protein intake (2-3g/kg seems optimal)
2) progressive mechanical loading

i.e. A fixed proportion of calories should be comprised of protein, this should be prioritised over other nutrients when apportioning calories to macros, and you should  be engaging in a sensible weigh training routine.

From the above, we can derive the minimal, most simple, implementation to diet for fat loss:

Minimum implementation:
1) ensure calories are in deficit of requirement
2) ensure sufficient protein is included in this calorie amount
3) engage in regular weight training with a focus on progressive overload.

One addendum here, while not a requirement for maximal fat-loss would be to include a few servings (100g/serving) of fruit and vegetables. There’s a tendency to use IIFYM as a loop-hole excuse to get all your carbs from marshmallows and while, in a theoretical sense, this would still work, we should still acknowledge micro-nutrition and satiety – Yusef wrote a very comprehensive guide on this here.

You can then boil down progress to the following 2 metrics:
1) Weight loss or gain
2) Strength loss or gain

– > dropping weight and maintaining strength – you’re going to look better, no questions asked
-> slowly gaining weight while increasing strength – you’re gaining muscle with minimal fat

So, to successfully implement the above, the required actions are:
1) follow sensible macros matched to your goal, track them
2) evaluate your change in weight weekly/monthly
3) Measure and track your progress on barbell/dumbbell/machine lifts

The beauty of this is, it is the simplest approach possible while still ensuring progression. Any less intervention would impede progress and any further intervention is not a requirement.

Because of this, we can now determine a decision framework to decide whether we should make any subsequent intervention, remember, the goal is to be as happy as possible in life and minimise unnecessary stress and unhappiness.

Lets assume you’re considering a different diet approach, consider the following:
1) If I don’t make this change, can I still respect rules 1-3?
2) Does the change increase or decrease my utility?

I’ll run through some examples to illustrate:



1) If I don’t follow the paleo diet, can I still respect rules 1-3?  – Yes
2) Do I get intrinsic utility from avoiding gluten, dairy etc? –  No
Decision: don’t implement

The common response here is “but I think I may be allergic to xyz”. If you have reason to think this, namely, you are actively experiencing digestive discomfort or other allergic responses that seem to correlate with certain foods or meals, try eliminating ONLY this food for 4 weeks and see if the symptoms improve. If you think you’re allergic to gluten because the Paleo world says you are, you most likely aren’t. We obtain the most robust immune system from eating a varied diet and improving the quality of gut flora so the goal should be for the most INCLUSIVE diet as possible and only restrict specific foods as a last resort.

– Restricting gluten (or any other food) makes usual social outings difficult and more or less restricts you to home prepared food.
– The decrease in utility via social and personal stress must be matched by a greater gain in utility by alleviating digestive discomfort and allergic response.
– Put simply, foods should be eliminated ONLY if absolutely necessary.

The goal is to restrict as few foods as possible, providing maximum flexibility within the framework in which we operate.  

This said, some people do gain some level of personal pride purely from eating “cleaner” than others. If you decide to just eat a varied diet that includes some food that you like, you may experience some criticism from these people. If think they’re better than someone else because they’re eating clean, so, inherently, they derive their self-worth from being positively perceived.

Well, I’d rather focus on the basics, eat food I enjoy and plough my effort into training hard and tracking macros, have sharper abs and a bigger squat than the guy who spent all morning worrying about whether his venison might have come into contact with wheat at some point. Let these people do as they please and watch as they stare, perplexed, as you throw down some skittles, espresso and a shake as your pre-workout.


Consider, what is more impressive: Looking lean but only ever eating certain foods or having abs while rarely turning down a meal out with friends and eating what you enjoy?


1) If I don’t fast, can I still respect rules 1-3? Yes
2) Do I get intrinsic utility fasting? Yes/no
Decision: If yes, by all means, fast, just remember that it’s no big deal if a few days per week you want some breakfast – as explained above and don’t stress about specific fasting windows, it’s not a primary driver. By the same token, if you want to eat breakfast – go ahead.

Tracking macros:

1) If I don’t track macros, can I still respect 1-3? – No
If you don’t know your food intake, even roughly, its hard to make accurate outcome based decisions – you may get leaner/bigger but you won’t know why. Tracking your food is such a powerful tool that, even if it does slightly decrease your utility now, you’ll get used to it and it’ll be worth it in the future.

Decision: implement


Back to IIFYM. Lets consider, really what this is:

We predict our calorie requirement and set planned intake as a metric of this: less than maintenance calories for fat loss, and more than maintenance for muscle gain. We then determine the macronutrient composition. Per the above, protein should be between 2-3g/kg and then the remaining calories from any split of carbs and fat (I always suggest fat is at least 15% of calories for both hormonal and satiety reasons).

The only remaining diet requirements: eat some fruit and veg, take a multi-vitamin and get at least 20g fibre.

What does the diet have to be past this? Whatever you want. We can worry all we want about meal timing, food choices, carb timing but what we know is, none of these things are needed. You don’t have to eat sugary convenience food, pastry and cake – but you can if you want.

IIFYM gets hate because of false extrapolation and mis-interpretation. It doesn’t have to be “dirty” food and it doesn’t have to be “clean” but thats why it works so well, its a beautiful expression of complexity filtered into simplicity.

As I write this I’ve tracked macros for over 500 days consecutively and not eaten a single pop-tart in that time….. I know, I know, I’m crazy.

Over these 500 days my rate of progress has been the best it’s ever been – why?

Effort applied to the basics on a brutally consistent basis

I eat a varied diet of foods I enjoy, hit my macros and bust a gut under a barbell 4-5 times per week, I no longer care when I eat my carbs, I don’t care if I eat out, drink on occasion or miss a meal – I care about hitting my macros and adding weight or reps and I care about enjoying life in the process.

Could I have made better progress if I had worried about these things? Maybe. But thats not the point, even if I would have, I’d never know. What I would know is that I would have sacrificed a hell of a lot over those 500 days for a marginal, immeasurable difference in progress. The key – I’m as happy as I can possibly be while getting better every day and I’d trade marginally slower progress (if at all) for happiness and a social life in a heart beat

But hey, you want to lock yourself away and obsess over detail? Be my guest, the rest of us will leave you for dead in a cloud of icing sugar.

The Next Step

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