Clean Eating vs. If It Fits Your Macros (IIFYM): What You Need to Know

Clean Eating vs. If It Fits Your Macros (IIFYM):
What You Need to Know

There has been a lot of discussions both in the media and in doctors’ offices about the obesity epidemic this country is facing. While everyone has heard that diet and exercise is the way to fix this, there is an overwhelming number of diets to choose from. Is a meat based high protein diet better than plant-based? Do you need to go dairy-free or gluten-free? With the sheer number of options, people often jump from diet to diet when they don’t see continuous weight loss. The result? People to become frustrated over time as they don’t reach their health goals or struggle to stick to their program. 

One school of thought you may be familiar with touts that counting “calories in versus calories out” is the answer; indicating that it is energy balance and not the type of calorie that matters. However, it can be argued that not all calories are created equal. Every diet requires you to consume a balance of nutrients like protein, fat, carbohydrates, vitamins, and minerals, but there are different types of carbohydrates, fats, and even proteins that can make “the right” decision difficult. 

Two diets that bring the age-old question of quantity versus quality into the light are “Clean Eating” and “If It Fits Your Macros (IIFYM).” Even though many people have been frustrated by past failures with diets, it is important not to give up! In this article, we are going to explain a bit more on what these two diets are, how they’re different from other diets, and how these diets impact body composition.

Body Composition: What Is It?

Body composition is more descriptive than overall weight because it reports what is really making up that body weight. Weight is comprised of lots of different components including protein, water, minerals, and fat. Combining all these components determines someone’s body composition.

When dividing the body into different components, usually the most focused upon is body fat. Clearly, there is cause to be concerned about fat mass, which is why fat loss is the selling point for many diets; however understanding the balance between lean mass, fat mass, and water is just as important when it comes to maintaining a healthy body composition. 

Diet is a crucial factor in maintaining a healthy, balanced body composition.

The Clean Eating Diet

Clean eating is less of a diet and more of a lifestyle. There are a few important points when it comes to clean eating, such as:

Eating more nutrient-dense whole foods and fewer processed foods or “refined” foodsFocusing on eating full, balanced meals and fewer snacks Eating more at home where people can control what goes into their meals Sleeping more at night and exercising regularly.

These points show that focusing on healthy eating habits and getting the right food groups places fewer restrictions on your diet, giving you some freedom; plus, there are also scientific studies to back up the claims. 

A study published in the British Medical Journal followed over 10,000 people and collected their dietary information. This list included more than 3,000 different foods and they were categorized by their degree of processing. 

What the researchers found was that ultra-processed foods were associated with dramatically higher cancer risk, specifically breast cancer. The researchers also attempted to adjust the results to account for sodium, lipid, and carbohydrates. However, no matter how they interpreted the data, processed foods led to higher chances of developing cancer.

Another research study looked at the impact of processed foods in pregnant women on the gestational weight gain and size of the baby. The research data was collected from St. Louis, MO and analyzed the links between the mother’s diet and the body composition of the baby. The researchers found that:

On average, more than 50 percent of the daily calories in these women came from processed foodsA 1 percent increase in the percentage of processed foods resulted in an additional 1.33 kg (close to 3 pounds) of weight gain during pregnancyThis same percentage increase led to a 0.62 percent increase in the body adiposity of the baby

This is important because excess gestational weight gain can lead to maternal hypertension, gestational diabetes, and possible pre-eclampsia. 

By eating clean and avoiding processed foods, people can improve their body composition and overall health. Many people have trouble eating clean because of the “convenience” factor. It is important to remember that foods can be both convenient and healthy. Just reach for foods such as fruits, vegetables, lean proteins, and nuts before you succumb to junk food.

A study published in the British Journal of Nutrition echoed this sentiment. Researchers studied a few dozen adults who increased their intake of fruits or vegetables. The researchers found that not only did this lead to decreased food intake (measured in energy) but it also led to a reduced waist circumference and weight loss. 

The Takeaways: Clean Eating

Clearly, clean eating not only leads to weight loss but improves body composition as well. By improving body composition, individuals can improve their overall health and reduce their chances of developing dangerous complications of obesity down the road. 

For people who embrace “clean eating,” they focus on a higher intake of fruits, vegetables, and protein without getting caught up in counting the number of calories. This diet might be right for people who get frustrated by counting calories and would like an overall “big picture” to which they can adhere.

“If It Fits Your Macros”

Another diet that people may have heard about is the “If It Fits Your Macros” diet, also called IIFYM. For those who have trouble counting calories, the IIFYM diet could provide more structure. The macronutrients or “macros” include:


All of these components impact overall health and body composition in a different way. The diet isn’t “low carb”. Nor does it make specific recommendations like eating lots of healthy fats or whole grains. Instead of focusing on a “one-size fits all approach,” you calculate your macros to tailor the diet to your specific metabolic demands. Then, people are allowed to eat whatever foods they would like as long as it fits their individual macronutrients. 

An interesting research study included hundreds of thousands of people and, over a period of several years, swapped the percentages of their dietary macros. Then, they tracked their weight at follow-up visits. 

Some of their results showed that swapping fat for protein led to weight gain, swapping carbohydrates for protein led to weight gain, and diets with 14 percent protein were associated with less weight gain than diets with 20-25 percent protein.

While these individuals may have been building lean muscle mass with this increased protein intake, the results still show that diets with excess protein can cause someone to become overweight and obese. Too much of a good thing is possible. Everyone needs to ingest all macros in the right amounts, which can be different from person to person. Some people need more healthy fats or whole grains depending on their lifestyle. Swapping the amount of each macro that you eat on a regular basis impacts both lean muscle mass and fat mass.

Another study published in the Journal of Nutrition took a similar approach. In the study, participants around the age of 45 were randomly placed into two different energy-restricted diets which were either moderate in protein or high in carbohydrates. The individuals had their body composition measured at four months and then again at 12 months.

At the four month mark, the protein group had lost 22 percent more fat mass than the carbohydrate group, but the overall weight loss did not differ. At 12 months, the protein group had higher adherence to the study with a greater improvement in body composition, but weight loss still did not differ much. Finally, the protein diet provided an overall greater improvement in body composition along with a greater reduction in triglyceride levels and a more significant increase in HDL.

This study shows that, while either diet can help someone lose weight, each macro impacts body composition differently. Diets that have a significant amount of protein in them might not help someone lose more weight than a high carbohydrate diet, but it can help someone build more lean body mass. Importantly, it can also help someone lose fat mass and might be easier to adhere to.

Furthermore, strict one-size fits all diets often do not work because people cannot stick to them. In fact, for some people, indulging a little bit can actually help them stick to a diet while still remaining within their macros. A study published in the Journal of Consumer Psychology highlighted that:

On occasion, indulging while on a diet can help someone regain their ability to self-regulatory their intakeIndulging can also help people maintain their motivation to stick to their dietThis also has a positive impact on their mood, which helps them stick to their goals

With this in mind, if people can indulge while still adhering to their macronutrients, it could help them stick to their diet. If they are able to adhere to their diet, they are more likely to attain their goals. The point of this is that the “right” diet for someone ultimately needs to be one with which they can stick to.

The goal of the IIFYM diet is to provide everyone with an individualized dietary structure that allows for more to hit the plate than just chicken and veggies. However, the IIFYM diet goes beyond basic calorie reduction or counting and acknowledges that every macro impacts body composition in a different way. 

With this in mind, the IIFYM diet provides everyone with a plan that is tailored for them and their goals. The IIFYM still asks people to count calories and to calculate and track their macros, but it provides comfort to those who like to have structure and also allows them to eat foods that they like.

Adhering to a Diet

There are many different diets that people have heard about and everyone talks about finding the “right” one. Ultimately, many people become frustrated because they have trouble sticking to a diet or feel like they aren’t seeing results. For this reason, the “right” diet is the one that you can stick to.

Clean eating and IIFYM diets each have their merits and can be successful for different people. But remember, a diet can be successful even if people aren’t losing weight. The goal isn’t just to lose weight but to reach a healthy balance of fat mass and lean body mass. It is vital to focus on body composition as a marker of overall health instead of just the number on the scale. If the weight stays the same but there is body fat loss and lean body mass gain, this should still be viewed as progress. 

A diet will not work if people are not fully invested and if the individual does not feel like they can stick to the eating plan. In the end, remember that diet is a slow but proven process and the approach to improving body composition needs to be well-rounded and easy to maintain. Aim to discuss your dietary plans with a nutrition professional to ensure that you are losing weight in a healthy manner and choosing the diet that works best for you.


David Randolph graduated from medical school at the University of North Carolina in Chapel Hill. He is currently completing his Residency in Pediatrics at the University of South Carolina.


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