It Should Fit Your Macros (ISFYM): The Ideal Diet to Meet Anyone’s Needs

A lot of attention has been given to the If It Fits Your Macros (IIFYM) diet approach in the health and fitness industry. In this article I’m going to address the benefits of this diet, the drawbacks, and much of the science and intention that has been lost in recent years. I’ll speak on the science of nutrition regardless of your diet choice, the basics of weight gain and weight loss regardless of your food choices, and the long term health affects of your food choices. The goal of this article is to shed some light on the foundation of nutrition and how someone with a basic understanding can maximize their diet and nutrition while still reaching all their goals!

The basics of nutrition is and always will be calories consumed. Everyone has a resting metabolic rate (RMR) that is the baseline amount of calories they will burn while at rest for that day. It is largely dependent on age, height, weight, and sex but can vary from person to person. Men and women will have a slightly different RMR, but on average will fall between 1,400 and 1,700 calories. Knowing your own RMR will allow you to increase the calories as needed for the additional exercise, sporting events, or activities for that day. Someone who is more active will need to increase their calories greatly above their RMR, while someone who does little physical activity may not need the same increase. It is important to remember that one’s RMR is the calories needed while RESTING, therefore you should not decrease calories below that level (very low calorie diets are bad!). When it comes to weight loss or weight gain, you are manipulating the ADDITIONAL calories above your RMR.

When people think of “dieting”, they usually associate it with trying to lose weight. In order to to lose weight, you must be in a caloric deficit, no exceptions. This can be done in one of two ways. First, consume less calories. Seconds, burn more calories. Most choose a happy medium when trying to lose weight and choose to restrict calories as well as increase exercise, therefore consuming less and burning more to reach their weight loss goal. When trying to lose weight people typically think to eat fruits, vegetables, lean sources of meat, and/or as many natural foods as possible. A dissociation between the food choice and the results of that choice often occur, however. Many people will say that because they are eating a fruits, vegetables, and other “healthy” choices, they are losing weight. When it fact they are losing weight because fruits and vegetables have very few calories. No different then if they ate one bite of a candy bar… but who does that?! When in a calorically restricted diet, the quality of food choice becomes even more important. This is because the important micronutrients you will likely easily get in a normal, balanced diet may be harder to get when you have fewer total calories to work with. When you are restricting your calories, your quality of food needs to be well-balanced in the micronutrient categories. This is why you see many people choosing fruits, vegetables, and lean meat sources when dieting. They cover all aspects of nutrition while having “less room to work with” so to say.

On the other side, anyone wishing to gain weight must be in a caloric surplus. Because most people who are wishing to gain weight are doing so for a sport related event, reducing exercise is an undesirable option. So in this case, they must consume more calories to reach their caloric surplus. Individuals with a high RMR (“fast metabolism”) or high activity level will find that they need to consume much more calories than they may have originally thought. Because you now have more calories to consume, you will likely be eating a larger variety of foods and definitely more quantity. This makes it easier to get both your macro and micronutrients in because of the variety of foods you will consume. Because foods that are traditionally looked at as “unhealthy” have higher a caloric content, they can be a desirable option for someone who has difficulty gaining weight. As long as they continue to incorporate foods rich in micronutrients such as fruits, vegetables and a variety of other food choices, they will get the best of both worlds as far as macro and micronutrients. At times it is simply unrealistic to try to put on a lot of weight while eating traditionally “clean” or “healthy” foods because these foods are often low-calorie. By being aware that calories are calories in terms of weight gain or loss, you can find that happen medium to reach your goal.

So now that you have the basic understanding of food choices and the role calories play in weight gain and weight loss, how do you begin? The first step is to set a goal weight. The second step is to take action. This process is likely thought of as a blood, sweat and tears approach to reaching your goals. But what if I told you it is actually more mathematical than physical? It takes roughly 2,500 additional calories above one’s caloric requirement to gain one pound and 3,500 calories below to lose one pound. Needless to say, it is both unhealthy and unlikely that someone will lose or gain a large amount (> one pound) of weight in a day. If this does happen, it is likely due to water weight. A better approach would be to slightly restrict or increase a portion of the total calories (2,500 or 3,500 depending on your goal) each day and meet your total that week. For example, if I wanted to lose a pound a week I could decrease my calorie intake by 500 calories each day and reach my 3,500 deficit on the 7th day to lose one pound. As you can see, I have not mentioned anything about food choices. That is because weight management is calorie dependent, not food choice dependent.

Knowing all this, you can see how someone may see the high variability in food choices to reach these calorie totals. For instance, if I were to eat a snickers and soda I would consume 11 grams of fat, 67 grams of carbs, and 3 grams of protein. If I were to eat a cup of oatmeal, a banana, and a teaspoon of peanut butter I would consume 10 grams of fat, 62 carbs, and 6 grams of protein. The food choices themselves are much different but the overall caloric content is very similar. As far as weight loss and weight gain go, there will be no difference between the two choices. This is the basis of the IIFYM approach to diet. Eat whatever you want, as long as you meet your caloric goals for the day..because it will give you results. As far as aesthetics are concerned this approach is exactly right. However, I would suggest that the second options is a much better one due to the added benefits of the micronutrients and quality macronutrients. But lets not rely on my opinion, lets look at the research that has been done when comparing these types of food choices and diets. 

As is often the case in most scenarios, people can over time misinterpret and push the limits the originally intended purpose. I believe the original purpose of IIFYM was to help people realize that it is the total caloric content they should be PRIMARILY focused on and not to view foods as either bad or good. Over time that intention has turned into the “I can eat whatever I want, it doesn’t matter” mentality. Studies have shown that people do need to be educated on their diet and pushing an IIFYM way of dieting may be blurring the lines. For instance, the World Health Organization proposes a limit of 25g of added sugar a day and a 16oz bottle of Coke has 52g (more than 2 days worth) of sugar. The average 5 year old consumes the equivalent of their body weight in sugar in one year! Those are just facts though, what’s the relevance? Well, sugar drinks have been linked to 3x higher prostate cancer risk as well as an increased risk of developing diabetes. An additional study showed that carbs from whole foods were linked to 67% lower breast cancer risk and a lower occurrence of diabetes (likely due to insulin fluctuations). Although a balance of “good” and “bad” foods is not a bad thing, viewing all foods as equal (in this case thinking that all carbohydrates are the same) can potentially lead to deficiencies that can cause health problems.

Micronutrients are not needed in the same amount of macronutrients (as the names would imply…micro-small, macro-large) but that does not mean they are not important because less is needed. It is true that a well-balanced diet will likely covers most, if not all, of your micronutrient needs. But if you are one of the IIFYM dieter’s and abuse the ability to choose your foods, you will likely fall short of these vital micronutrients. In order to appreciate the power of food outside of what carbohydrates, fats, and proteins can do for you, I would suggest you look a food from a more holistic approach. Western medicine may be the most extreme example of pushing pharmaceuticals to cure disease and eliminate pains, but this style of medicine hasn’t always been around although the problems likely have. I am not proposing we rely entirely on food for all our problems, that would be both inefficient and ineffective in certain instances, but I would suggest to value the micronutrients and compounds that have been shown to have drastic health benefits in certain instances and populations. For instance, celery has very few, if any real calories (often referred to as a “negative calorie” food). With an IIFYM approach it is a unneeded food. However, luteolin which is found in celery has been shown to activate the longevity pathway, increase mitochondrial biogenesis and energy expenditure. Not bad for no carbohydrates, fats or proteins.

Food should not only be viewed as what it does to your physical appearance, but also the hormonal and cellular responses to food choices. One study showed that types of fat consumed effect hormone response differently, meaning not all fat elicited the same response. When individuals consumed saturated and monounsaturated fats, testosterone levels showed an acute rise. This relationship was not seen when consuming trans and polyunsaturated fats. If your daily goal is to reach 90 grams of fat for the day using the IIFYM approach, whether you consume brazil nuts or peanuts does actually matter (like anything, likely over time and consistency). The same is true for foods containing high amount of sodium and potassium. There is an ideal balance in the cells and interstitial fluid to maintain hydration (termed “osmolality’) and this can be disrupted when electrolyte levels get skewed. By manipulating sodium and potassium levels you directly affect the hormones aldosterone and vasopressin. Aldosterone is a steroid hormone and helps regulate sodium and potassium levels in the body, balancing fluids and electrolytes helping to conserve water indirectly. Vasopressin is a anti-diuretic hormone causing a rise in blood pressure and constricts the blood vessels. Manipulation of these two electrolytes is a common practice for extreme weight cuts, but you should be aware you are losing water weight not real weight! Aside from the macronutrients and there effects on the body, fiber has also been shown to have extreme health benefits. One study showed that people with the highest fiber intake had ~80% greater chance of living long & healthy life out of all food factors. That is extremely powerful for one dietary variable! Even more astonishing when looking at JUST fiber (out of all the factors they examined including total carbohydrate intake, glycemic index, glycemic load, and sugar intake) it made the biggest difference in healthy aging. Healthy or “successful aging” as used in the study was defined as “an absence of disability, depressive symptoms, cognitive impairment, respiratory symptoms, and chronic diseases including cancer, coronary artery disease, and stroke.” Although there is countless amounts of research supporting food choices matter and the effects of various vitamins, minerals, and micronutrients, I’ve only listed a few examples to hopefully spark your interest to dive a bit deeper in understanding nutrition!

So where did IIFYM go wrong? IIFYM was originally proposed as the 90/10 in old school bodybuilding. In a sport entirely based around how you look, aesthetics are the number one goal. It is important to understand that how you LOOK is entirely dependent on the amount of calories you eat. This is the foundation of IIFYM. You set a total calorie goal, and your carbohydrates, fats, and protein make up percentages of that total caloric content. The food you choose to eat to make up those carbohydrates, fats, and proteins is up to you. The original 90/10 method then turned into the 80/20 method of dieting (80% of food being what people would consider “clean” and the remaining 20% being whatever you wanted). The difference between the 90/10 and 80/20 method of IFFYM results in zero differences in physical appearances. As this became a more acceptable way of diet and nutrition, people pushed the limits and today you see people drinking energy drinks, donuts, pizza, etc. as long as they meet their total goals for the day.

However, this style of dieting can be beneficial for some. As is the issue in many areas of fitness, adherence seems to be higher in most people following IIFYM style of eating. With caloric intake being the primary issue with weight loss and weight gain, if someone can stick to a diet longer, they are more likely to reach their goals! The benefits of choosing a diet like IIFYM is, therefore, adherence. People are much more likely to stick with a diet program they enjoy with as few restrictions as possible. It’s a simple and effective way to reach you bodyweight and aesthetic goals, without a doubt. However, you should be cautious and aware of what you are putting into your body, and not get caught in the trap of “I can eat whatever I want, it’s in my diet plan” type of mentality.

I would propose that rather than take the IF it fits your macros approach, you take the IT SHOULD fit your macros approach. Do not lose sight of the important fact that your body operates on a CELLULAR level first and foremost. As originally intended, the 90/10 shows insight on the importance of “clean”, “healthy” foods while allowing the 10% of “unhealthy” foods to likely increase adherence. The ISFYM says that in an ideal world, 100% of your caloric content goals for the days come from macro and micronutrient dense foods. Foods that will help you reach your carbohydrate, protein, and fat goals as well as your vitamin and mineral goals.

Food choices such as chicken breasts, turkey, lean red meat, roast beef, and salmon are excellent choices for protein. Nuts, nut butter, cooking oils, and avocados make for good fat choices. Rice, pasta, oatmeal, sweet potatoes, yams, fruits, vegetables, quinoa, and lentils make for good carbohydrate sources. You are certainly not limited to those foods, but they are just some good options to help get you on the right track. After looking at the nutritional profile, you can begin to make selections of your own that include a wide variety of macro and micronutrients. I would also encourage you not to just view the label, but the ingredients as well. The longer the ingredient list, the more processed and artificial a product you will be consuming in most cases!

Don’t Forget!

Absolutely tracking your calories (IIFYM) is a much better/healthier option than not doing so. There is a ton of research supporting low calorie diets alone as huge health benefits. ISFYM is for someone who is willing to look at things a bit deeper and is more dedicated to an overall health approach. Let’s not forget about the numerous benefits of exercise alone, regardless of diet, has on the body anti-aging, disease reversal, increased life expectancy etc. I am just proposing that you not settle for IIFYM or lose sight of the goal…to be healthier in all aspects of life both today and tomorrow.

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