What Is the If If It Fits Your Macros (IIFYM) Diet?

In the early 2010s, social media platforms exploded with fitness accounts run by bodybuilders, powerlifters, CrossFitters and other exercise enthusiasts. This was before the age of the influencer, but said fitness enthusiasts would share their workouts and meals online much like fitness and wellness influencers do today. 

One popular style of eating, as evidenced by a quick hashtag search on Instagram, was IIFYM, which stands for “If It Fits Your Macros.” Still popular today, the IIFYM hashtag spits back images of incredibly toned and muscular people enjoying chocolate cake, double cheeseburgers and other yummy high-calorie foods. 

In simple terms, IIFYM is a dieting theory that stipulates that food type isn’t the most important factor. Instead, the individual macronutrient is the most important factor. It kind of boils down to a “calories in, calories out” approach without much focus on food quality. 

What Can You Eat?

Also called flexible dieting, a pro of the IIFYM lifestyle is that you can eat anything you want—as long as it fits your macros. “Macros” refers to macronutrients which include carbohydrates, fats and protein.

Each macronutrient has a specific caloric value per gram:

• Carbs and proteins have 4 calories per gram
• Fats have 9 calories per gram

By measuring the gram amount of each macronutrient you eat in a day, you should reach an intended daily calorie intake in line with your health and fitness goals.

Everyone has different macro “prescriptions” based on their biological sex, height, weight, activity level, body composition and goals. 

IIFYM Diet Example

Take fictional John for example: John is six feet tall and weighs 200 pounds. He’s pretty active guy and eats about 2,500 calories per day to maintain his current level of fitness. He lifts weights and enjoys active hobbies, so he prioritizes protein and carbohydrate intake (but is mindful that because of his desk job, most of his day is spent sitting). At 35 years old, he wants to preserve muscle mass and stay lean. 

John’s macros look like this (refer to table below): 203 grams of protein (812 calories from protein), 233 grams of carbs (932 calories from carbs) and 85 grams of fat (765 calories from fat). That totals out to 2,509 calories, which is just enough to support John’s activity level and keep him healthy despite his sedentary job. 

With that 2,509 daily calorie allowance, John can eat anything he wants as long as he meets (or almost meets) his macros, which refers to the gram numbers for each macronutrient. John can tweak his food intake to satisfy cravings and hunger on different days. 

For example, on most days, John might get his 233 grams of carbohydrates from whole-wheat bread, rolled oats, rice and starchy vegetables. On another day, he might decide he wants something sweet, so he eats non-starchy vegetables at dinner and fulfills his remaining carb allowance with ice cream. 

What You Need to Know

The IIFYM lifestyle encourages an eating pattern with no end date rather than a restrictive regimen with a deadline. 

IIFYM is nothing but a numbers game, so if you enjoy data, you can thrive on IIFYM. On the other hand, if you prefer more of a free-eating approach that doesn’t involve counting, weighing and measuring food, IIFYM may not be the proper eating style for you.

You Will Need to Weigh and Portion Food

While long-time macro-counters can accurately eyeball portion sizes, people new to IIFYM will find themselves spending a lot of time portioning and weighing food. IIFYM requires dedication and consistency for the first several months (and a lot of research on the macro content of different foods), and many people don’t make it past those few grueling months. 

Many people who count macros carry portable food scales with them and stick to strict eating regimens, while others take a more laissez-faire approach and don’t stress it if they don’t hit their macro targets.

Sample Shopping List

Shopping for IIFYM can feel easy or hard, depending on how you look at it. You have complete food freedom on this eating plan, so you can purchase whatever you want or need to reach your macros.

Many people who have success with IIFYM enjoy both healthy, nutrient-dense foods along with “fun” foods that may not have as many micronutrients.

• Protein sources: eggs, chicken, ground beef, pork chops, beef jerky, whey protein
• Carb sources: rice, pasta, quinoa, granola/cereal, oatmeal, bread, tortillas, starchy veggies, fruits
• Fat sources: nuts and seeds, avocados, oils, fish, cheese, Greek yogurt
• Snacks: chips, pretzels, granola bars, popcorn, dried fruit, trail mix

Sample Meal Plan

IIFYM doesn’t require meal timing or any other restrictions. The only requirement is that you reach your macronutrient goals every day or on days you count (some IIFYM followers give themselves leeway on weekends and don’t count). 

Let’s backtrack to our John example (remember, his macros are 203 grams of protein, 233 grams of carbs and 85 grams of fat). A day of eating for an IIFYM follower like John might look like this: 

Breakfast:

• 50 grams of protein
• 60 grams of carbs
• 20 grams of fat

Snack:

• 20 grams of protein
• 30 grams of carbs
• 5 grams of fat

Lunch:

• 40 grams of protein
• 60 grams of carbs
• 15 grams of fat

Snack:

• 20 grams of protein
• 20 grams of carbs
• 5 grams of fat

Dinner:

• 70 grams of protein
• 60 grams of carbs
• 10 grams of fat

Dessert:

• 5 grams of protein
• 100 grams of carbs
• 30 grams of fat

Summed up, that day of eating comes out to 205 grams of protein, 230 grams of carbs and 85 grams of fat. While not a perfect 2,509 calories, it’s pretty close. It’s important to remember that, if you choose to follow this diet, striving for perfection isn’t realistic.

Pros and Cons

Pros 

Complete Food Flexibility, Variety

The primary benefit of IIFYM is that it doesn’t restrict the types of foods people are allowed to eat. Most other diets restrict food groups or require strict meal timing, whereas IIFYM has no rules—except to meet your macros. 

Makes Shopping and Meal Planning Easy

Because IIFYM allows such great flexibility, grocery shopping is easy. You won’t find yourself making meticulous lists or purchasing ingredients you’ve never heard of before (unless you’re a fan of trying new recipes, in which case, have at it!).

If you decide to start IIFYM, there’s a good chance your grocery list will include a lot of your usual items, taking one stressor off of your plate. 

Can Help People Lose Weight and Improve Body Composition

Many people, especially bodybuilders, weightlifters and CrossFitters, have seen tremendous success on IIFYM. The macro approach allows them to focus on food as fuel for their workouts, driving them to become better athletes.

IIFYM can also work for the everyday person who just wants to lose weight or body fat, especially when done in conjunction with an exercise program. 

Can Be a Low-Cost Diet Option

Because there are no food restrictions, IIFYM is more cost-accessible than other diets. You won’t have to purchase expensive pre-made foods or organic ingredients to reap the benefits of IIFYM. 

Cons

Can Feel Tedious and Cause People to Give Up

Portioning out every morsel of food that goes into your body may become tedious. It can get old really fast, which is why so many people give up on IIFYM. The weighing and measuring is a bona-fide barrier to entry. Some people can’t stick to measuring long enough to achieve good eyeballing skills, so they may not see any results (or the desired results) from IIFYM. 

Takes a Long Time to Get Comfortable 

It takes a lot of practice to reach the point where you can accurately eyeball portions of food and know you’re reaching or at least getting close to your macros each day. Many people give up before they reach that point, which makes the diet unsuccessful. 

Can Encourage Unhealthy Food Choices

Some people take advantage of the flexible dieting approach and use it to justify eating unhealthy foods day-in and day-out. While there’s absolutely nothing wrong with enjoying foods that aren’t rich in micronutrients, it’s scientific fact that human bodies need micronutrients to function optimally.

The lack of focus on micronutrients in IIFYM leads some people to exist solely on packaged, processed foods as long as they reach their macros. 

May Lead to Disordered Eating Habits

The emphasis on macro counting leads some people to become hyper-focused on the numbers. This can be detrimental and result in emotional distress about food, particularly in the sense that the person feels owned or controlled by food — rather than feeling in control of their food intake.

If you have a history of disordered eating or have had an eating disorder diagnosis, IIFYM is probably not the best approach for you. Talk to your doctor or psychologist about possibilities and alternatives. 

Is IIFYM a Good Fit For You?

IIFYM isn’t for everyone, but many people do find success with this approach. You might thrive on IIFYM if you enjoy eating a wide variety of foods and can hold yourself accountable to choose primarily healthy foods to reach your macros. If you have specific health and fitness goals and love using data as an objective measurement of your progress. IIFYM might be a great fit for you. 

On the other hand, IIFYM might not be the right diet for you if you already struggle to choose nutrient-dense foods, as the lax approach might discourage healthy eating choices.

Also, if you feel overwhelmed or restricted by the thought of weighing and measuring your food, you probably won’t enjoy IIFYM.

Health Benefits

Let's take a look at some of the potential health benefits of the IIFYM diet.

Encourages Food Variety

A healthy diet includes a range of foods containing many different nutrients. This is achievable with IIFYM because no foods are restricted. However, it’s up to the individual to choose nutrient-dense foods that fit their macros over nutrient-poor foods that fit their macros. 

Can Aid Weight Loss 

Like mentioned earlier, IIFYM is basically glorified calorie counting, and this can help some people reach weight loss goals. IIFYM is a great approach for people who currently have no clue how many calories they eat each day and need a baseline to go off of. 

Can Fine-Tune to Fitness Goals

If you view your body as a machine and food as fuel, counting macros might help you get the most out of your workouts. IIFYM allows you to manipulate the variables of your meals to consume carbs, fats and proteins when it’s most beneficial to your body and your performance. The vast majority of people don’t need to incorporate meal timing, however, and should first focus on building a foundation of basic healthy habits. 

Health Risks

While there are no common health risks associated with IIFYM, this diet approach can lead some people to develop disordered eating habits. It can also discourage healthy eating habits by encouraging people to choose nutrient-poor foods as long as they eat the right amount of carbs, fat and protein. 

Also, the IIFYM approach doesn’t take into consideration people with medical conditions.

For example, an online macro calculator might tell a person with diabetes that they should eat 200 grams of carbs per day based on their height, weight and other information.

But in reality, a person with diabetes should carefully monitor their carbohydrate intake to avoid blood sugar highs and lows. 

A Word From Verywell

Like all diets, IIFYM has its pros and cons. This diet is a good choice for some people, while others will find themselves struggling with the constant weighting and measuring. Because IIFYM promotes food freedom, it’s worth trying if you’re searching for a structured yet flexible way to meet your nutrition goals. 

Remember, following a long-term or short-term diet may not be necessary for you and many diets out there simply don’t work, especially long-term. While we do not endorse fad diet trends or unsustainable weight loss methods, we present the facts so you can make an informed decision that works best for your nutritional needs, genetic blueprint, and budget, and goals.