When's the best time to use IIFYM?

By now nearly everybody in the fitness community has heard of ‘IIFYM’ (If It Fits Your Macros). There are a lot of advantages to this way of dieting, but we at RP also want to talk about WHEN there is a best time to adapt a more flexible approach and when it might be a better idea to be a bit more rigid on your food composition.

There are 3 main dieting phases that we’ll use for this article:

  • Massing (trying to gain weight)
  • Maintenance (trying to maintain weight)
  • Cutting (trying to lose weight)

Knowing those three distinct phases, we can start to talk about the advantages and disadvantages of a more IIFYM approach.

When it comes to Massing, the answer here for IIFYM should be a resounding YES. When you’re trying to gain weight (especially if you have recently ended a cut) this is the PERFECT time to be a bit more relaxed on your diet in terms of food composition. We know now that dieting (to lose weight) by definition is not a lifestyle and since it is by definition restrictive it is NOT sustainable. This means that we have to have designated periods where you are actively focusing on not losing weight or stressing about it (read more here about the importance of maintenance). This ties perfectly into the more relaxed approach for eating when trying to gain weight. Being able to sneak in your favorite types of foods when massing allows you to go out and live life without having to feel ANY guilt whatsoever since you’re purposely trying to be more relaxed. It should also be noted that this assumes you’re staying within the recommended guidelines of gaining about 1lb per week (maybe a bit more for heavier folks and a bit less for lighter individuals). So long as you’re within those guidelines and so long as you are hitting your macros and eating a reasonably healthy diet for most of your meals, you should absolutely eat what you want 100% guilt free.

When massing, a more IIFYM style of eating also offers the distinct advantage of having lower volume foods to help you pack in all of the calories that you might need. If we can envision a 200lb male needing hundreds of grams of carbohydrates on a hard training day, being able to eat sugary cereal and skim milk after a workout is a LOT easier than trying to choke down 2-3 large sweet potatoes and veggies!  After all, we know that food composition is a smaller detail in the grand scheme of diet effectiveness, so this is absolutely a good approach to adapt when you run into the issue of being TOO full when eating to gain weight.


On to the second phase….Maintenance. When it comes to maintaining weight, the answer to the question of whether or not it’s a good time to go to a more IIFYM style of eating is another resounding YES. We know, from earlier, that dieting to lose weight isn’t sustainable in the long-term, so for most folks this is where you will likely spend the vast majority of your time. Nobody (not even the most hardcore bodybuilder out there) is a robot and can be rigid on their diet year-round. This means that when maintaining you can afford to be a bit more flexible in your approach. You might not be able to be quite as relaxed as when massing – you want to stay within a few pounds of your weight on average – but, knowing that your weight can remain stable, it makes sense to enjoy some of the foods that you really love.

Some of the same advantages apply when maintaining as they do when massing.  Tastier foods are generally lower in food volume, so it serves as a benefit for those needing large amounts of food to maintain their bodyweight. This plays perfectly into relaxing after a long diet where you likely had to be a bit stricter (which leads us into the last phase).

Cutting phases can be a bit stricter since we know they are simply not sustainable over lengthy periods of time and there’s no need to fear some strictness because we don’t NEED it to be sustainable. Nobody can or should diet for many months on end while being super strict; the dieter will eventually start seeing diminishing returns on performance, mental health and on their ability to maintain muscle. This means that one should focus on tightening up things while trying to lose weight (read more about that here).  When calories become restricted to lose weight, each calorie matters more and more for a number of reasons, and satiation (how much a food helps you stay full) is one of the biggest factors.  As we said above, tastier foods don’t tend to be very satiating as they are lower in food volume – so they’re just not a great choice on a cut!


The picture above does a great job at illustrating the biggest takeaway of this article. There’s a clear time and place to implement a more IIFYM style approach to dieting. When lowering calories to lose weight, IIFYM just isn’t as good an idea as is a more “clean eating” approach (our definition of “clean eating” is eating less junk food and focusing on more lean proteins, whole grains, healthy fats, and fruits/veggies).

Let’s recap:  Reasons an IIFYM approach is less effective when dieting:

  • Smaller food volume. Inevitably when dieting you’re going to become hungry. Being hungry is most likely lead to folks to want to cheat on their diets. If you can help stay more full while dieting, your chances of success should increase. Picture needing 40g worth of carbs and you eat a cup of oatmeal vs eating several Oreos. The cup of oatmeal is going to help keep you a lot more full than eating a couple of cookies. See the image below on which foods promote more feelings of fullness.


  • Increased cravings. Using the above example of oatmeal vs Oreos, it’s going to be fairly obvious that one of those choices is more likely to make you crave more. It’s quite rare to be able to find an individual that can only eat just 1-2 cookies vs an entire row (I think we’ve all been guilty of that from time to time). Dr. Mike Israetel talks about this in our latest ebook “Understanding Healthy Eating”, “The Food Palatability Reward Hypothesis (FPRH) is another very fancy concept that boils down to a simple observation: people eat more tasty foods than more bland foods.

If you have lower volume foods when cutting and that leads you to be hungrier, the odds of experiencing food cravings go up as well. Combine the two of those together and all of a sudden those cravings can get out of control; you’ll very likely find yourself eating more than you should, thus severely impacting your ability to lose weight.

  • Less Micronutrients. Using our oatmeal vs Oreos example, the Oreos and other more heavily processed “junk” foods will typically have less vitamins and minerals in them. Although this is a lower priority when it comes to dieting for body composition, it is a consideration to factor in when calories are being restricted while on a cut.

The above reasons all play a role into why IIFYM style isn’t quite as effective as a “cleaner” eating approach while dieting. That is not to say that it can’t ever be used when dieting, as personal preferences need to be factored in as well. So long as you know and are ok with the tradeoffs involved, then it’s ultimately up to each individual to make their own personal decisions on how they go about approaching the dieting phase. We just want to lay out the tradeoffs so that people like you can make the most informed decision when dieting.

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