The IIFYM (If It Fits Your Macros) Diet: Yes, No, or Maybe?
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At any given time, almost half of the adult population in the U.S. (49.1%) is trying to lose weight. Others follow a specific meal plan in an attempt to boost muscle mass.
As a fitness professional, clients will look to you for dietary advice. They want your input when trying to reach their specific goals. How does the IIFYM diet fit into this conversation?
What Is the IIFYM (If It Fits Your Macros) Diet?
IIFYM is a weight loss diet that stands for “if it fits your macros.” It involves eating a menu that fits within a specific macronutrient ratio. The exact carbohydrate, protein, and fat intake will vary. It is based on a person’s individual situation and needs.
Proponents tout IIFYM as a flexible diet approach. As long as you stay within your recommended ratio and calorie count, you can eat whatever foods you want. That makes this weight loss approach appealing to people who are tired of restrictive diets. It allows them to eat their favorite foods and still lose weight.
How the IIFYM Diet Works
The first step to following the IIFYM diet is determining the total calories your body burns daily. This is known as your total daily energy expenditure or TDEE. Then, eat 20% less than this amount. This creates a calorie deficit large enough to burn excess body fat.
One way to determine your body’s calorie needs is to calculate this number by hand. To calculate TDEE, you add:
- Basal metabolic rate (BMR) – how many calories your body burns at rest
- Thermic effect of feeding (TEF) – how many calories you burn to digest the foods you eat
- Exercise energy expenditure (EEE) – how many calories you burn while exercising
- Non-exercise activity thermogenesis (NEAT) – how many calories you burn doing non-exercise activities, such as playing with your kids or walking up the stairs at work.
Essentially, TDEE is how many calories you burn between both physical activity and simply staying alive. It tells you how many calories your body burns in a typical day.
In addition to staying within a certain calorie intake, you must also monitor your intake of the three macros. As a reminder, these are carbs, protein, and fat. This helps preserve lean muscle while supporting optimal weight loss.
Calculating Optimal Macronutrient Intake
Determining your maximal macronutrient needs is a bit trickier. That’s why some people use an IIFYM calculator instead. This provides a daily caloric deficit goal, along with the desired carb, fat, and protein intake. It also takes into consideration a variety of other factors. Among them are your sex, age, height, weight, body fat, activity level, food preferences, physical health, and more.
When calculating macronutrient intake by hand, the right combination depends partly on the client’s goals. For instance, if their intent is mainly to lose weight, a diet high in protein and fat and lower in carbs can help achieve this goal. Yet, if they want to build muscle, carbs and protein are often higher, with fat being lower.
The client’s body type may impact their macronutrient recommendations too. Endomorphs typically do better on a low-carb diet whereas ectomorphs can handle more carbs. Mesomorphs may see more results by balancing their carbs, protein, and fat.
Benefits of Monitoring Your Macro Intake
Counting macros does offer a few benefits. First and foremost, it ensures that your body gets the right amount of each nutrient category. This supports healthy body function. The better your body operates, the more efficiently it can lose weight.
Research has shown that there is a relationship between macronutrient intake and weight. One study noted a correlation between macronutrient consumption and body mass index (BMI). By eating foods in all three macro groups, people were able to lower their body weight. They also had sustainable weight loss.
Following a macros diet may also be beneficial for people with certain health conditions. This diet takes physical health into consideration. So, it can be tailored to not instigate these issues. The medical diagnoses IIFYM asks about when doing an online calculation are diabetes, Hashimoto's disease, polycystic ovary syndrome (PCOS), and menopause.
Many health experts support calorie counting and macronutrient counting to better control some of these conditions. In an article published in the Journal of Social Health and Diabetes, researchers call eating within a certain macronutrient range a “central pillar” of nutrition therapy for people with diabetes.
Research in the journal Reproduction states that reducing calorie intake can help treat PCOS. Additionally, many of the studies involving PCOS and diet follow a specific macronutrient intake. That is, though being lower in calories, they each stayed within certain ranges for each macro. These ranges were 45-65% carb, 10-35% protein, and 20-35% fat.
Drawbacks of the IIFYM Diet
Although flexible dieting has its advantages, it also has a downside. Because it only looks at total calorie count and macronutrient intake, it is easier to make not-so-healthy food choices. Junk food isn’t off-limits, nor are processed foods. But if you eat too many of either, it can impact your health and weight.
You may even experience weight gain when following a flexible dieting approach. Since many processed foods contain added sugar and higher amounts of sodium, it can throw off your body’s normal hunger and satiety cues. Cravings increase as you struggle to feel full.
Or you fill up on foods that don’t offer much nutritional value. Technically, they may meet the diet’s guidelines. However, they might not supply enough of the micronutrients the body needs to function optimally. This can inhibit your fat loss, making it harder to lose weight.
Is This Diet a Yes, No, or Maybe?
There is no one-size-fits-all diet that works for everyone. And each one has its pros and cons. The most important thing to remember when a client asks for advice is to learn more about their weight goal and lifestyle. For the diet to work, it must work with these two factors.
If the client eats mainly healthy foods but is interested in finding the right macro combination for them, the IIFYM diet may be a good approach. It takes the guesswork out of putting a menu plan together. It provides a framework that can help them better reach their goals.
If you get the impression that the client views this type of diet as permission to eat a lot of unhealthy foods—as long as they fit in the calorie and macronutrient specifications—then it’s important that they understand that losing weight at the risk of their health isn’t the best goal. Food quality is still a major consideration, even if this diet doesn’t reinforce it.
Ultimately, it is up to the client what type of diet they follow. As their fitness trainer, you can provide the information needed to help them make an informed decision. Check in with them regularly to keep track of their diet. If it isn’t supporting their weight loss, suggest modifications. If you see a change in their performance, explain how their diet may be contributing.
Tips for Success When Following the Macro Diet
If the client decides to follow the IIFYM diet or any other type of diet that involves counting macros, help them understand the nutritional values of food. Talk with them about the difference between a healthy fat and unhealthy fat food source. Explain a simple carb versus a complex carb.
Give them the information they need to ensure that their bodies get the highest quality macronutrients possible. Also help them recognize the value of taking in adequate micronutrients. Vitamins and minerals further support proper body function. That makes them a critical part of the fat loss process.
Additionally, take this opportunity to reinforce healthy eating habits. This includes eating mindfully and chewing slowly. Don’t allow distractions at the dinner table and take the time to enjoy your food. Losing weight isn’t just about what we eat. It is also about how we eat, where we eat, and the whole eating experience.
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