Feed yourself with what it’s needed to fulfil your mental and physical demands.
IIFYM stands for If It Fits Your Macros, a style of eating that allows you to pursue any weight-related goal without restricting foods. You meet your calorie target by “hitting” certain amounts of each macronutrient (in grams), regardless of source. In other words, you can eat anything, as long as you can “fit” it into your calorie requirements.
In my short series of articles on nutrition, I mentioned that 1 gram of each macronutrient corresponds to a certain amount of calories:
Technically, although we tend to use the colloquial term calories, they should be referred to as kilocalories, which is also the unit used on all food labels. You need 1,000 calories to make up 1 kilocalorie.
For the sake of simplicity, I will keep calling them calories throughout the article.
That said, IIFYM in simple terms is another way of counting calories. In fact, most people count both calories and macros and have specific targets for each.
IIFYM sounds like an easy way of keeping your nutrition in check without falling into the disordered eating trap of classifying foods as “good” or “bad.”
If you have ever tried it, though, you might have questioned at least one of the following:
In this article, I’ll give you an answer to each question and practical tips to take your IIFYM diet to the next nutritional level.
*A note on alcohol: Alcohol isn’t a macronutrient (sorry, folks), but it does contain calories, so that’s why it’s included here.
When accounting for alcohol intake, you can log the calories from your alcoholic drinks as fat, carbs, or a combination of the two.
For example, if you drink 460 kcals of alcohol, you could log them as 115 gr of carbs, 52 gr of fat, or 93 gr of carbs and 10 gr of fat. This comes down to whether you want to have more calories left for carbs or fat for the rest of the day.
Q1: Why don’t calories and macros match?
The reason is that neither calories nor macros are 100% correct on nutrition labels.
Calories can be off by 20-25% in either direction. For instance, the label might state that 100 gr of a certain product contain 100 kcals. In reality, those 100 kcals could be anything between 75 and 125.
Furthermore, companies can round grams up or down, for example 9.2 gr of protein can be rounded down to 9, whereas 3.8 gr of fat can be rounded up to 4 gr.
Accounting for this level of variability is impossible, but that doesn’t mean counting calories or macros is a waste of time. It just means you don’t need to worry too much if you don’t hit your macros perfectly every day.
Instead, you can set a calorie target and a range of 5-10 gr for each macronutrient.
The calorie target should align with your body composition goal, be that maintenance, muscle gain, or fat loss.
The macronutrient targets allow you to be in the right ballpark of protein, carbs, and fat to achieve your fitness and lifestyle goals (more on this in response to Q3!).
Q2: Do you count the protein in carbs?
The protein in most carbohydrate sources is incomplete, so it doesn’t contain all the nine essential amino acids needed for muscle maintenance and growth, and other physiological functions.
For this reason, I have an “overall” protein target and a “complete” protein target. First I set my “complete” protein target, then, for every 100 gr of carbs I eat, I add 10 gr of protein to this. The result is the “overall” protein target.
For instance, if you’re eating 300 gr of carbs every day, your goal is to gain muscle, and your current bodyweight is 150 lbs, your overall protein target would be 180 gr. 150 gr would come from complete protein sources (1 gr per pound of bodyweight), whereas the remaining 30 gr would come from incomplete sources.
The credit for this method goes to Steve Hall, who recommended it on Instagram a while ago.
As an alternative, you can also track just calories and complete protein instead of every single macro. This is an easier way to do it, but it’s also less precise, so it might be counterproductive unless you already have a high-level awareness of your own nutrition and of which foods contain which macronutrients.
Q3: Low-fat or low-carb? Does it matter?
What matters most is your protein target. This is especially important if you have fitness goals associated with muscle growth or fat loss. Even if you don’t have any such goal, it could be argued that protein is a fundamental nutrient for anyone.
The ratio of carbohydrate and dietary fat, on the other hand, depends on a number of factors.
If we’re talking about fat loss, a meta-analysis from 2018, comparing the effects of low-carb and low-fat diets, found negligible differences between the two in terms of impact on BMI, cholesterol, quality of life, and other markers.
So, once again, the best diet is the one you can adhere to the most.
However, if you’re trying to gain muscle, the approach you follow matters a little more. I say “a little” because, as long as you (1) train hard, (2) eat more calories than you consume, and (3) eat an adequate amount of protein, you will build muscle.
Fine-tuning carbs and fats may make a difference in terms of the ratio of lean mass versus body fat gain, but I would only worry about that if you already met the three abovementioned conditions almost every day.
So what’s the ideal ratio for muscle gain?
On one end of the fat-carb continuum, you could choose an extremely high-fat diet. That is, sticking to a bare minimum of 0.3 gr of carbs per pound (30 gr for a 100-pound individual, 60 gr for a 200-pound individual).
This way, you could eat less food to achieve the same surplus as a higher-carb diet, which may make it easier to stay in a surplus if your calories are very high or if you don’t have much of an appetite.
On the other hand, you wouldn’t have as much energy to train, as this energy is provided by the glycogen stored in your muscles. Glycogen comes from carbohydrates, not dietary fat. As a result, you might experience more fatigue and a reduction in performance over time.
In addition to this, it can be easier to accumulate body fat on a higher-fat, lower-carb approach.
This is because a caloric surplus means excess energy. Energy comes primarily from carbohydrates and from dietary fat as an alternative source. However, if it has fuel to spare, the body won’t find any need for dietary fat and will simply store it away as adipose tissue (body fat).
You can and will put on some body fat even if you choose the high-carb approach. Excess energy is still more than the body requires to maintain its functions and current weight. However, excess carbs might be more likely to be converted into energy instead of adipose tissue.
Depending on the circumstances, carbs may be used up immediately; stored as glycogen in your muscles and liver as energy for future use; or stored as fat when glycogen stores become full.
Furthermore, on an extremely high-carb approach, eating around 0.3 gr of fat per pound, you would have plenty of energy for your training, which means you can tick off condition (1) for muscle growth.
You would also secrete more insulin than on a low-carb diet, as insulin is produced in order to reduce blood glucose levels. Like glycogen, glucose comes from carbs.
Now, insulin gets a bad rap because, as an anabolic hormone, it encourages our body to store dietary fat as body fat. However, it also encourages the synthesis of protein and carbohydrate, two nutrients you need for muscle gain. So insulin helps you tick off both conditions (1) and (3).
The downside to the high-carb method is that it’s more restrictive than a higher-fat or a middle-of-the-road approach, since many foods that are high in protein and carbs are also high in fat. So it might not be feasible unless you were happy to cook 90 to 100% of your meals at home.
In addition to that, it’s a lot more food than you would need on an extremely high-fat approach, which might not be feasible for people requiring 3,000 calories a day or more to create a surplus.
At the moment I’m on a low-fat intake, which equals about 0.5 gr per pound of bodyweight, so I’m in the higher-carb, lower-fat camp.
This works well for me because I prep most of my meals, I prefer carbs over dietary fat, and, being 5’1” (oh, joy), I need fewer calories than an average person to generate a surplus.
Note that the two methods outlined are two ends of a spectrum, not the only two possible. For example, if you ate between 0.3 gr and 0.5 gr of fat per pound instead of hitting 0.3 gr bang on, you would be at a reasonably low level of dietary fat intake to get most of the benefits of a high-carb diet.
Similarly, if you were to eat between 0.3 gr and 0.5 gr of carbs per pound, yours could still be considered a low-carb approach.
Nevertheless, don’t think that you have to be super extreme for your diet to “work.”
If the range given looks too restrictive, you can also hang out somewhere in the middle of the spectrum and see what’s more effective and more sustainable for you in the long term.
Q4: Is IIFYM healthy if you can eat anything you want?
For one, you technically can’t eat anything you want. Unless you want to gain an unhealthy amount of body fat very fast, you still need to be somewhat strict about hitting your macro ranges and your calorie target.
Nevertheless, following this style of eating, some might still fill up on excessive amounts of nutrient-poor foods, like chips and cake.
This is the biggest limitation of IIFYM: the excessive focus on macronutrients.
As a nutrition coach, I know that there’s a lot more to your nutrition than carbs, fat, and protein. Vitamins, minerals, water, and fibre are just as important, but are often overlooked by the IIFYM crowd.
My answer to the question is a definite yes, IIFYM can be healthy, but only as long as you are aware of the importance of the other components of a balanced diet.
So, if you want to have the odd pack of Oreos or piece of cake, be my guest, but make sure that you balance that out with fruit, vegetables, whole grains, lean protein, and healthy fats.
If you have any other questions about IIFYM, you can comment on this post or get in touch with me directly. If not, have fun on your IIFYM journey.
In Future Episodes:
A reflection on my experience with resistance training and nutrition over the past year: physique changes, mindset changes, mistakes made, and lessons learnt.
What does your current way of eating look like?
A personal trainer who likes superheroes, bread, lifting weights, and studying “fitness stuff”.
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