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If It Fits Your Macros: You Need to Know the Truth

The crux of this ‘diet’ is that you can eat absolutely everything you want (yes, even pizza), as long as it keeps within your daily macronutrient goals.

Can IIFYM work? In some cases, yes.

Is it optimal? No. And anyone who works in the real world with real clients will know this.

The aim of this piece isn’t to rant about the evils of IIFYM, but to discuss our experiences of what we feel works and doesn’t work in the IIFYM model.

Having delivered exceptional transformation results with thousands of clients, we know what to do when it comes to body re-composition.


What is IIFYM?

The original intention of IIFYM was to allow you a little bit more flexibility with your diet, rather than restricting yourself to a limited number of ‘clean’ foods, such as chicken and broccoli.

However, what started as an alternative name for ‘sensible eating’ has morphed into a pro-junk food diet where anything goes, as long as it ‘fits your macros’.

A Calorie is a Calorie…

To lose body fat you need to be in a calorie deficit.

‘Calories in vs calories out’ is, and always has been, the number one factor in improving body composition.

The first step for anyone looking to get into better shape should be to get your calorie intake in order.

But does this mean you can have your cake and eat it (quite literally)?

The calories in vs calories out model suggests that you could eat chocolate cake for breakfast every day and this would still help you keep the weight off in the long run.

The problem with this formula is it assumes all calories are equal, and that humans are robots disciplined enough to be able to consume a small piece of cake and then leave it at that.

If your goal was solely weight loss, looking only at calories may be a viable option.

However, our goal with clients is to transform their body by building muscle and losing body fat. To do this, we need to consider the composition and quality of calories consumed.

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If we look at the first popular form of IIFYM, Weight Watchers, one of the issues was a low protein intake.

If you’re following a calorie restricted diet that is deficient in protein, you will be susceptible to muscle loss, and the ‘soft, saggy’ appearance you commonly see in chronic dieters.

The first step is to aim for a daily protein intake of 0.8 to 1.2g per pound of your bodyweight.

In an IIFYM-type diet, it wouldn’t matter what types of foods you ate to satisfy your protein target.

Foods such as tofu, bread, rice and beans all contain protein, but they are ‘incomplete’ protein sources, which means that they don’t provide all the amino acids (building blocks of muscle) needed by your body.

The majority of your protein intake should come from ‘complete’ protein sources, such as beef, chicken, salmon and eggs.

You also need to consider the distribution of your protein intake across the day. For best results, you can’t just eat a kilo of steak for dinner.

Eating protein stimulates the muscle building process (protein synthesis), but you only need so much to trigger this response. Consuming a large percentage of your protein intake in one sitting misses the opportunity to stimulate protein synthesis more often throughout the day.

Take your daily protein target and split it into three to four protein based meals spread evenly across the day.



The easiest way to explain the difference in carbohydrate quality is to pose this question:

Are 100g of carbohydrates from sugary sweets the same as the equivalent amount provided by sweet potatoes?

From an energy standpoint, it’s the same. But you also need to take into account the difference in the insulin spike that each will give, and the effect this will have on blood sugar control and satiety.

100g of carbohydrates from sugary foods, especially those high in salt, will only leave you craving more of the same after you’ve finished.

These types of food also contain far more calories per serving compared to alternative carbohydrate sources, such as fruit, vegetables, potatoes and rice. Emphasising the latter will allow you to eat a greater volume of food, which will keep you feeling fuller for longer.


Having a wide range of fats in your diet is important.

Saturated (animal fat, eggs, coconut oil, butter), monounsaturated (olive oil, avocado, nuts) and polyunsaturated (fish oil, flax seed) fats all have a role to play in keeping your body functioning optimally.

A common mistake made by people following the IIFYM diet is to either eat a very low-fat diet to free up more calories for junk food, or for a large percentage of their fat intake to come from highly processed junk food.

The focus of any proper diet should be to include a moderate fat intake from a wide range of sources, with additional support from a high-quality fish oil supplement.

What are some of the lesser-known implications of IIFYM?

1. Digestion

Most of our clients are highly stressed and have years of bad eating and lifestyle habits behind them.  As a result, their digestive systems are not functioning anywhere close to optimally.

Further overloading an already dysfunctional system with pop tarts and jelly babies to reach a certain quota will only backfire.

Between 70% and 80% of your immune system is found in the gut, which means that keeping it healthy is paramount for your overall health.

Within only a few days of starting a transformation with us, clients always rave about their new-found energy levels.  When we clean up their diets by introducing high-quality foods, the gut starts to function more efficiently and begins to extract the energy it needs from food properly.

An important note to consider is that sometimes even the best single-ingredient foods don’t agree with everyone. For example, eggs are common allergens, and some people don’t feel great after eating them.


2. Micronutrients 

If you’re using your fat and carb quota to eat junk food, then chances are you’ve got some micronutrient deficiencies.

Micronutrients are not only important for your ability to recover from training, protect from injuries and lose body fat, but also for your overall health. If you’re not healthy or have a weak immune system, you’re going to find it hard to build muscle and lose body fat.

While you may be able to get away with eating like this in your 20s, it will most likely catch up with you in your 30s and beyond.

3. Bodybuilder’s edge

If you want to study how to get lean, look no further than those who do it best: bodybuilders.

If IIFYM is as great as it’s been made out to be, why is it that even the absolute genetic elite aren’t using it?

Bodybuilders have known for decades now that to get lean you need to do three things:

  1. Create a calorie deficit,
  2. Cut out junk food,
  3. Do this for an extended period of time.

At the most competitive level of bodybuilding, everything matters and they are all looking for the extra edge. The fact is no one at the top level is using IIFYM.

If it were a superior method of eating for optimal body composition, bodybuilders would be using it.

How would we integrate IIFYM?

There are some good principles in IIFYM that you can introduce to your dietary approach. What IIFYM has opened our eyes to is that there is more to life than simply chicken and broccoli.

It does provide some flexibility into your diet that can be beneficial from an adherence and mental standpoint; two overlooked factors in successful long-term dieting.

The key phrase here is ‘long term.’ Short, dramatic transformations in regular people very rarely come from adopting an IIFYM approach.

If long-term maintenance and slower results were the aims, then you could allow a more ‘flexible’ approach with the occasional ‘treat’ to help ensure adherence.

We like to call this ‘sensible eating.’

The second instance whereby including some elements of IIFYM works well is for our muscle-building clients who are pushing the ceiling when it comes to calorie intake.

In such cases, including 10-20% of your calories from less traditional ‘clean’ food choices can make life a lot easier. Of course, this is down to the individual client, and ultimately the decision should be based on what feels best for the client.
Lean and healthy


The message we wanted to put across in this piece is that there is more to macronutrients than meets the eye.

IIFYM will work if you want average results, but as industry leaders, we demand excellence through optimisation of all variables.

In the long run, a sensible eating approach is best.  This means basing the majority of your diet on a wide variety of single-ingredient foods.

Any time someone tells you junk food on a daily basis is the ticket to get lean, your BS-meter should be going through the roof.

In an industry filled with gimmicks, fads and false promises, if it sounds too good to be true, it more than likely is!


Jakubowicz, D., Froy, O., Wainstein, J., & Boaz, M. (2012). Meal timing and composition influence ghrelin levels, appetite scores and weight loss maintenance in overweight and obese adults. Steroids, 887-889.

Mamerow, M., Mettler, J., English, K., Casperson, S., Arentson-Lantz, E., Sheffield-Moore, M., et al. (2014). Dietary Protein Distribution Positively Influences 24-h Muscle Protein Synthesis in Healthy Adults. Journal of Nutrition, 876-880.

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