Clean Eating vs. IIFYM for Advanced Athletes

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It seems that you can’t look anywhere on the internet without being bombarded with fitness individuals showing off their ice cream, cookies and other fun foods while touting how they are getting leaner with “fitting their macros!” On the other hand, you have fitness individuals showing their countless boring meals of lean chicken breast, brown rice and broccoli. Most people, without hesitation, would be pulled in by the IIFYM (If It Fits Your Macros) approach – who wouldn’t want to eat those delicious foods all day long and still get in shape?!

It seems as if the two sides are constantly at war with each other on social media. Each side slams the other as being too extreme. As with most things, we’ll see in this article that the real answer lies somewhere in the middle of the two. This article will discuss the Pros and Cons of each side of the debate, and we’ll develop a true scientific approach to dieting to help athletes get into top conditioning.

Brief Overview of the Nutritional Priorities

This section has to be covered first before discussing the pros and cons of each dieting approach. We’ll keep it brief as to keep the focus on our topic at hand. The first nutritional priority and the most important is Calorie Balance. This means that in order to improve body composition (losing fat or building muscle) you must get your total calories figured out in order to see the best results.

The second nutritional priority is your macronutrient breakdown. This means that once you have your calories figured out, you must figure out your macronutrient breakdown for the day (how many grams of protein, carbs and fats).

The third nutritional priority is nutrient timing. This refers to meal frequency (how many times do you eat per day) and the timing of your macronutrients throughout the day. The first two priorities are far and away the most important, with nutrient timing coming in a distant third place.

Last and least important is food composition, which refers to the types of each macronutrient you are eating (complete vs incomplete sources of protein, high vs low GI carbs and saturated vs unsaturated fats).

For a more in-depth review of the Nutritional Priorities, please check out this YouTube video series by my colleague Dr. Mike Israetel:

Here’s a visual breakdown of the Nutritional Priorities:

C:\Users\Nick Shaw\Desktop\RP\Diet Success.png

Now that we have the priorities covered, we can discuss the benefits and possible drawbacks to each side of the argument.

Clean Eating Pros

    Almost all traditional bodybuilders have been following more of a clean eating approach for as long as bodybuilding competitions have been around. The three main benefits of clean eating are hitting your total calories, very likely hitting your daily macronutrient breakdown, and abiding by the food composition principle quite well.

This seems to fit with the general observations of bodybuilders and other physique competitors throughout the years, as they must doing something right in order to get shredded for the stage. They certainly are doing something right in that they have several of the priorities completely in line for improving body composition, and two of the most important ones. They reduce their calories (an assumption we can make based on the fact that most bodybuilders lose weight throughout their contest prep and end up stage ready) as needed to continue to lose fat and they have the right macro breakdown in place (or at least for the most part). What they also do very well is have their food composition in check. This means they’re eating predominantly complete and lean sources of protein while eating almost entirely lower GI carbohydrate sources throughout the day.


Clean Eating Cons

    The main thing that the clean eaters are missing is the role of nutrient timing. They are very likely eating multiple meals per day (picture those Tupperware photos all over Instagram), but the timing of macronutrients around activity is often missing almost entirely. While this is more of a detail in the grand scheme of things, when you’re competing on stage, the differences between first and second place are usually quite small. The competitive level is when details can really start to matter between that national qualification or top 5 finish vs going home empty-handed.

    In getting into the specific benefits of nutrient timing, it has been shown that even equated for carbohydrate amount; high glycemic index carbohydrates replenish glycogen more rapidly and completely than low glycemic index carbohydrates. Because high glycemic carbohydrates replete glycogen more effectively, and also because they cause a more profound insulin spike (and are digested rapidly to be available in the blood right after training), they should be consumed during and right after training for advanced athletes. When eating in a hypocaloric state (eating fewer calories than you are burning) the effects of nutrient can be amplified to ensure you retain as much muscle as possible. Again, this means that the details really matter. If you risk losing a pound or two of muscle while dieting, that is a BIG deal on stage.

    Another possible drawback of clean eating that shouldn’t be overlooked is that it can just plain suck. Eating more traditional “healthy” foods that can be boring can take a psychological toll on somebody that is dieting (a large reason that “cheat” meals play a role in clean eating). It surely seems a lot more fun to eat pop tarts, ice cream and Gatorade than it does to eat chicken breast, broccoli and rice.


    Much like clean eating, IIFYM does a great job of covering the basics. It nails down Calorie Balance (calories in vs calories out) as well as the macronutrient breakdown. Since it gets most of the priorities figured out, it can definitely lead to a lot of diet success. This is evidenced by the numerous transformation pictures available online of IIFYM success stories.

    IIFYM also likely does cover the role of nutrient timing around physical activity as most IIFYM’ers are eating higher GI carbs around the workout window and thus likely replenishing glycogen stores more adequately than their clean eating counterparts.

    As we touched on earlier with clean eating, another positive of IIFYM is that it encourages diet compliance. Eating delicious carbs throughout the day can really be an incentive to those new to dieting, and if they can see results, that’s certainly a positive as they’re more likely to stick to the diet.


    It’s going to seem like we’re nitpicking here as IIFYM gets the vast majority of the priorities in line for improving body composition. What we’re going to get into here is the role of food composition for body composition. The quality of your carbohydrate choices can play a role in determining how much muscle you can have and how lean you can get. There is data to suggest that if a diet consists primarily of high GI carbs vs. low GI carbs for all meals and over multiple weeks (lots of sugary treats for every meal), higher body fat levels and lower levels of muscularity result. This is a big factor in ultimate physique enhancement. If you’re going to lose a bit more muscle and retain a bit more fat that will absolutely mean the difference between placing where you want and placing where you ultimately do on stage. Sorry IIFYM’ers, this means that eating those delicious carbs all day long is just not the best strategy for enhancing your body composition. Our observations would support this claim as well as I’m not aware of too many high level bodybuilders that are eating ice cream while on a contest prep diet (sure some genetic freak exceptions do occur).

    Another downside to IIFYM is in considering the long-term health impacts of eating foods with a poor food composition or quality. McDonald’s fast food is tempting, especially if you’re getting leaner but the long-term health impacts can’t be overlooked. The role of trans fats in particular from eating junk food has virtually no role in helping to enhance body composition or for your overall health.

Scientific Dieting

    We now know that clean eating has a big role in enhancing body composition as well as IIFYM. Where do we go from here? As mentioned earlier, the real answer lies in the middle of the two. We know that clean eating is only missing the role of nutrient timing around activity and that IIFYM is just missing some adjustments to food composition. It now becomes quite clear how we can combine the two to really nail down all of the nutritional priorities. What results is a diet that consists primarily of lower GI carb sources, healthy fats and lean protein sources, with the exception coming around training. During and after training higher GI carb sources can be consumed to enhance performance and body composition. Let’s take a look at a sample day:

Meal 1 (pre workout) – lean protein source, healthy fats, veggies and a low GI carb source (think traditional bodybuilding meal of chicken, nuts, broccoli and rice)

Meal 2 (intra workout) – intra workout drink consisting of whey protein and a high GI carb source (Gatorade for example)

Meal 3 (post workout) – lean protein source and a high/moderate GI carb source (think sugary cereal or fat free fig newtons with whey protein)

Meal 4 (post-post workout) – lean protein source, healthy fats, veggies and a low GI carb source

Meal 5 (final meal of the day) – lean protein source, healthy fats, veggies and possibly low GI carb source

Final Thoughts

    Through the research of sports nutrition and our own observations of the top bodybuilders over time, we can come up with an approach that combines the benefits of each type of dieting strategy to give athletes the best chance to reach their body composition goals without any of the negatives.

    I can already hear the critiques that nutrient timing really doesn’t matter all that much, you’re focusing too much on the details, etc. To those who are saying that…we say you are correct! HOWEVER, in our quest to provide the optimal approach to improving body composition these seemingly small details absolutely can play a role for competitive athletes, especially athletes looking to compete at the highest levels. There is going to be suffering that occurs to diet down to that godlike physique on stage, but adding in elements of sports nutrition can hopefully reduce that suffering and enhance the overall body composition of physique athletes simultaneously.

    If you’re a beginner and are looking to make some improvements, clean eating or IIFYM can both yield very productive results. For the competitive athlete looking to take things up a level, fine-tuning some of the details and improving upon either clean eating or IIFYM can give you an edge in an already super competitive field.

Related Articles: The Clean Eating Conundrum and My Switch To IIFYM by Jen Comas Keck

Straight Talk About Serious Dieting by Dr. Mike Israetel 


Benefits of Nutrient Timing:

Role of Food Composition – Glycemic Index & Body Composition

Trans Fats & Body Composition

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