The world of nutrition is awash in different diets, and it’s safe to say that many of them hinge on rules surrounding what you can and can’t eat: nothing post-caveman for the Paleo diet, nothing from an animal for vegans, no fruit or grains on slow carb, and so on.
This is why the “If It Fits Your Macros” diet, also known as IIFYM, is seen by many as revolutionary. This method of eating allows you to eat anything from any food group — so long as it fits your macros. You’ll gain or lose weight if you’re consuming the right amount of calories, and you’re more likely to gain muscle and lose fat if you’re eating the right balance of protein, carbohydrates, and fat.
Editor’s note: The content on BarBend is meant to be informative in nature, but it should not be taken as medical advice. The opinions and articles on this site are not intended for use as diagnosis, prevention, and/or treatment of health problems. It’s always a good idea to talk to your doctor before beginning a new fitness, nutritional, and/or supplement routine. None of these supplements are meant to treat or cure any disease. If you feel you may be deficient in a particular nutrient or nutrients, please seek out a medical professional.
That’s IIFYM in a nutshell: keep your calories and macros in check, exercise appropriately, and your weight and body composition will improve. Want to make some buttery buffalo chicken? No sweat; watch your quantities. Does that coworker’s birthday cake tempt you? Have a slice; just deduct it from your daily calorie allotment.
For many, tracking calories feels very restrictive. In contrast, for others, IIFYM is an unbelievable breath of fresh air after years of “clean food” diets consisting of chicken, broccoli, rice, and absolutely no pizza ever.
What Is “If It Fits Your Macros” (IIFYM)?
If It Fits Your Macros is a diet that has the user track their macronutrients — protein, carbs, and fats — to ensure they’re consuming enough calories (in specific ratios) to lose, gain, or maintain weight.
IIFYM promotes dietary freedom, which is a significant reason why it’s gained so much popularity among physique and strength athletes. As long as you hit your macronutrient target, you can, in theory, eat whatever you want. The idea is that 30 grams of carbs — whether from vegetables, cereal, or pizza — is 30 grams.
How Does IIFYM Work?
IIFYM works by keeping people in a calorie range that suits their goals and then using this calorie target to distinguish the amount each macronutrient contributes to these calories.
The success of IIFYM is predicated on the idea that weight loss is primarily a matter of energy in versus energy out. If you burn more calories than you consume, you’ll lose weight. And if you eat more fuel than your body uses, you’ll gain weight.
“At the end of the day, whether you gain or lose weight comes down to calorie balance, and the macronutrients you use to comprise your total daily calories can exert a significant effect on what kind of weight you gain or lose,” says New York-based registered dietitian Leyla Shamayeva, MS, RD. “Speaking broadly, athletes typically want to gain as much muscle as they can when they’re trying to bulk, and they want to lose as little muscle as possible when they’re trying to cut.”
Based on this idea, calorie-counting is enough to either lose or gain weight. By counting your macros, however, you’re able to more precisely give your body the nutrients and macros it needs to build muscle or lose fat while maintaining muscle. Say you eat 2,000 calories worth of Doritos and Swedish Fish all day — you’ll lose weight on paper, but your body won’t have the materials necessary to carve out the physique you want.
Tracking your food intake is vital to long-term dietary success because even if you are not counting calories, the calories you eat will still affect your weight over time. (1) Ignoring your bank account doesn’t mean you don’t have money issues, and not paying mind to your food intake doesn’t mean calories don’t count.
The Origins of IIFYM
The seed of the current wave of the IIFYM diet, it’s fair to say, was planted by Mark Haub, a professor of nutrition at Kansas State University.
Haub is the man who is best known for his famous “Twinkie diet.” He ate a Twinkie every three hours for two months, along with corn chips, Oreos, and other processed snacks. He also consumed a protein shake and a multivitamin every day, practices that didn’t make quite as many headlines. The results? After two months of Twinkies every day, Haub lost 27 pounds and improved his cholesterol and triglyceride levels to boot.
How can he have improved his body mass and his heart health on such a junk diet? Because as much as we want to believe a trim waistline will just come from eliminating candy or dairy or red meat or anything else, the fact is that for almost everyone, the only thing that matters for weight loss is calorie balance. (This assumes you don’t have hormonal problems or other rare disorders that can interfere with normal metabolism.)
After two months of Twinkies every day, Haub lost 27 pounds and improved his cholesterol and triglyceride levels to boot.
Haub ate about 1,800 calories a day, and his daily calories needed to maintain his weight was 2,600. He, therefore, lost weight, and that’s good for your health and your heart. That’s all there is to it. The experiment received considerable media attention and renewed enthusiasm for flexible dieting.
Later, entrepreneur and fitness enthusiast Anthony Collova became well known for further popularizing the trend, launching a detailed macronutrient calculator at IIFYM.com to help curious dieters start their own experiments. People were successfully manipulating their body composition while making room for their favorite foods.
So What Are Macros?
There are three main macronutrients — protein, carbohydrates, and fats. Alcohol (aka ethanol) is technically the fourth macronutrient. Each macro plays a specific role in how your body functions and each macro contains a particular number of calories per gram:
- Protein: four grams
- Carbohydrates: four grams
- Fat: nine grams
- Alcohol: seven grams
The three main macros combined will make up your total caloric allotment. Once you know how many calories you need to eat to reach your goals, you’ll divide up a specific amount of calories to each macro.
There’s no one-size-fits-all ratio. Bodybuilders typically follow a 40-40-20 percentage split of protein, carbs, and fat. If you follow a keto diet, your ratio may look like 30-5-65. Athletes who require a lot of workout fuel in carbohydrates may eat a split that looks like 30-50-20.
Below, you’ll find a brief primer on protein, carbs, fats, and how all three impact your training goals.
Protein supports muscle retention and muscle growth, which is crucial because it allows you to continue burning calories at a rate that encourages weight loss. Eating more protein helps you to look your best and can aid in muscle recovery. It’s also a satiating macronutrient, meaning you get a lot of volume per calorie basis.
Protein is essential to consume before and after workouts to encourage muscle repair and growth. Still, research also suggests that protein can be consumed throughout the day rather than having it all at once to maximize the amino acids that protein provides. (2)
When setting up your macro targets, you should aim for a protein intake of 0.7-1 grams per pound of body weight, depending on how active you are. If you’re not very active, you can stick to the lower end of the range, but if you’re highly functional, you should use the higher end of the spectrum.
Carbs are the most efficient nutrient for supplying the body with the energy it needs to maintain organ function. (3) Carbs are also extremely important while exercising because they are the body’s preferred fuel source and therefore provide the energy you need to perform your best in training and recover after training. (4)
When your weight-related progress comes to a halt, you will typically add or subtract from your carbohydrate intake first. Carbs are adjusted before protein and fats because they are usually overconsumed by most people, especially those who are not tracking their macros or are not nutrient-conscious.
Carbs are also not as satisfying as protein and fats and, therefore, you can usually reduce them without getting too hungry.
The amount of carbs you should consume per day is usually determined based on the number of calories that are remaining from your daily calorie target after you’ve set your protein and fat targets.
Fats are essential for your health because they are required for some micronutrients to be absorbed (vitamins A, D, E, K). They can be anti-inflammatory and help regulate your hormones. (5) Therefore, at least 20% of total daily calories should be allocated to fats.
You can eat more fat if you prefer, but you will have to adjust your carbohydrate intake. If you’re more active, you’ll want to have a higher percentage of carbohydrates than fat. If you’re not as active, you’re probably okay with a higher fat to carb ratio.
Fats are the macronutrients with the highest number of calories per gram, but they are also the slowest to digest, so they will keep you full for longer periods. Therefore, eating a higher ratio of fat to carbs could help prevent you from getting too hungry throughout the day, which could help improve your adherence to your macronutrient targets.
How to Track Your Macros
Don’t worry if you’ve never weighed a gram of food in your life. Here’s a quick rundown of how to track your macros successfully.
Determine Your Macros
First, you need to figure how many calories you should be eating per day. It’s not a perfect science, but multiply your body weight by 11 if you’re looking to lose weight or by 15 if you’re looking to gain weight. From there, you can follow these general guidelines to calculate your macros:
- Set protein at one gram per pound of body weight.
- Multiply your body weight by 0.30-0.35 to find your fat intake.
- Divide the remainder of your calories by four to get the number of carbohydrates you should eat. (To find your calories, multiply your protein by four and your fat by nine, add those numbers together, and there you have it.)
If math isn’t your strong suit, then you can refer to this calculator below to get a good starting macro set:
Get the Right Tools
Once you’ve determined your macronutrient targets, you can begin tracking them manually or in an app. MyFitnessPal is a popular tracking app with an extensive food database and is compatible with different fitness trackers. Another option is Chronometer, which isn’t as compatible with other devices but does offer accurate food entries.
Next, you’ll need a food scale so you can weigh out all of your cooked and dry ingredients. (As a bonus: a food scale is beneficial to have in a kitchen even if you’re not into fitness and dieting.)
Eyeballing portion sizes without practice is difficult. What you think is four ounces of chicken may be seven — that’s a 100-calorie difference, which, over time, can derail your weight loss efforts. A food scale will ensure proper intake, whether you’re batch cooking or whipping up a single meal.
You’ll also want to snag a bodyweight scale and a measuring tape. It may sound obsessive, but tracking your body weight lets you know if your macros are optimal. For example, if you’re losing more than a pound a week, your macros are probably too low. Weighing yourself a few times per week also allows you to identify trends in your weight loss journey — like how much your weight fluctuates after a cheat meal and how quickly it takes to level back out.
The measuring tape is necessary because the number on your scale isn’t the only barometer of success. It’s not unusual for a person to lose only a few pounds over a few months but for them to lose a few inches off of their waist — which is a sign you’ve lost fat but maintain some muscle mass.
Choose the Right Foods
Apologies in advance, because if you’re jumping for joy at the idea of eating whatever you want while losing weight, prepare to take a seat.
“If you’re going to track macros because you like the freedom of choices, it’s important to realize that you should still choose healthy foods,” says New York-based registered dietitian Natalie Rizzo, MS, RD. “For example, you get a lot more pieces of fruit than candy within the carb allotment.”
Say your macros are 200 grams of protein, 250 grams of carbs, and 60 grams of fat. A slice of cheese pizza contains roughly 30 grams of carbs, 12-15 grams of fat, and 8-10 grams of protein. Those macros aren’t bad for “junk food,” but they’re not entirely balanced either. Eat two slices of za and half of your fat is gone for the day.
Common “junk foods” are high in calories from carbs and fats, and so eating them takes up a large amount of your daily caloric allotment while providing little to no protein and, frankly, not much satiation.
The best way to ensure long-term macro success is to build your daily meal plan around “single-macro foods” or foods that contain primarily one macronutrient. By choosing single-macro foods, you’re able to mix better and match different foods to create larger and more filling protein-dense meals.
For example, a Big Mac contains 540 calories and 30 grams of fat and 45 grams of carbs, and 25 grams of protein. Instead, you can make your own burger using 96% lean beef, low-fat or no-fat cheese, light mayonnaise, veggies, and a hamburger bun and slash the calories by 30% while keeping the protein the same.
Single-macro foods typically refer to what most people associate with being healthy foods — chicken, lean beef, potatoes, rice, oatmeal, egg whites, green leafy vegetables, and more. Of course, you don’t need to eat single-macro foods all day every day, but eating more of them will probably make hitting your macro goals easier.
Here are some food choices in each macro category that you can consider fitting into your eating plan:
- Lean Beef
- Cheese (low-fat and zero-fat cheese)
- Egg Whites
- Starchy vegetables
- Dark Chocolate
Plan Your Days
The best way to ensure you hit your macros day after day is to plan out your meals in advance. This way, you can pre-log your macros in your app of choice and not have to think about it.
It helps to choose meals that you like to eat day after day. Every week or so, you can switch up your food choices so you don’t get bored. As long as the macro profiles stay consistent, your food sources can change.
It also helps to try your best to plan out indulgences. If you know you’re going out to eat, leave room in your macros for a restaurant meal and maybe a drink. It helps to look up the restaurant’s menu ahead of time and pursue your options. Another tip for eating out: Always leave more room than you think in your macros. Oftentimes, restaurants cook with oils. So if you’re ordering a chicken dish, account for an extra 10 grams of fat or so.
Eating In Moderation On IIFYM
Although your primary concerns are staying within the calorie range and hitting the macronutrients targets, you should also be concerned about ensuring that the quality of food that you’re eating is sufficient.
Higher quality foods contain micronutrients (vitamins and minerals) that the body needs to function optimally and that help to reduce the overall risk for disease and illness. (6) Foods that are highly processed contain little to no micronutrients.
Micronutrients are nutrients that the body doesn’t produce itself, similar to macronutrients, but they’re called “micronutrients” because you need them in lesser quantities than carbs, fats, and protein.
“Your macros are important for reaching these goals, but it’s important to not forget about the ‘micros,'” says Shamayeva. “The more extreme factions of the IIFYM movement love to fill their days with hundreds, if not thousands of calories of junk food that happen to fit their macros. A calorie-controlled diet can make room for treats, but if you go too far in one direction then you can easily find yourself missing out on nutrients that are also important for your goals.”
However, just because you need micronutrients in smaller quantities doesn’t mean they aren’t important. If you’re not getting enough micros, you will likely feel sick, bloated, less energetic, and overall just feel worse than if you were to include them more regularly.
That’s not to say that a person can’t have these less nutritious foods in their diet, but they should include them less frequently and in smaller quantities while prioritizing higher quality foods most of the time.
A couple of ways that you could maintain this balance between more nutrient-dense foods and less nutritious foods is to pair them together. For example, if you want to have a donut, you could pair it with fruit to make it a more nutritious snack.
Or if you didn’t want to pair anything with the donut, you could prioritize more nutrient-dense foods in all other meals/snacks for the day so that you’re still getting all the nutrients you need in a day while enjoying the donut.
Also, taking extra supplements like a multivitamin and/or greens powder is a great way to help fill in the gaps in your diet.
Tracking your macronutrients using an IIFYM approach is a valuable tool to ensure that you’re getting enough of each nutrient to achieve your goals, whether that be weight loss, weight gain, body recomposition, or improved performance.
However, it’s important to understand what IIFYM is not, and that is an excuse to eat anything and everything just because you can. This diet is a tool that, when followed correctly, can teach followers moderation, the importance of food choice, and how to construct a meal plan that is doable for the long term.
While any food is technically fair game with IIFYM, there are some meals that are near-impossible to fit responsibly into most macro plans. A basket of fish and chips or a restaurant-style chicken parmesan can get close to (if not sometimes above) 1,000 calories and over a day’s worth of fats. The point of IIFYM is to fit smaller indulgences into your day of eating while keeping your total calories on track. However, certain occasions will arise where that’s not feasible — and that’s ok. If you’re at a birthday party and want to eat a double cheeseburger with bacon, do it, but then get back on track for the next meal.
The 80/20 approach to nutrition, where the goal is to eat nutrient-dense foods 80% of the time, and less nutrient-dense only 20% of the time, is a good guideline to follow on the IIFYM diet. If you want to get the most out of an IIFYM approach, then you need to be mindful of not only your macronutrient intake but also your micronutrient intake. If you feel like garbage but you’re hitting your macros, is it really going to feel worth it?
More Nutrition Content
The IIFYM diet is a reliable and time-tested tool that can help dieters achieve their goals with more freedom of choice. It still requires dedication, planning, and some sacrifice (any diet does), but for those looking to establish a healthier lifestyle — not just a short-term diet — IIFYM is for you. Here are some other nutrition articles from BarBend:
- The Different Types of Creatine Plus Their Benefits and Uses
- Everything You Need to Know About Mass Gainers
- What You Need to Know About the Vertical Diet
- Hill, J. O., Wyatt, H. R., & Peters, J. C. (2012). Energy balance and obesity. Circulation, 126(1), 126–132. https://doi.org/10.1161/circulationaha.111.087213.
- Schoenfeld, B.J., Aragon, A.A. How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution. J Int Soc Sports Nutr 15, 10 (2018). https://doi.org/10.1186/s12970-018-0215-1
- E Jéquier, Carbohydrates as a source of energy, The American Journal of Clinical Nutrition, Volume 59, Issue 3, March 1994, Pages 682S–685S, https://doi.org/10.1093/ajcn/59.3.682S
- Louise M Burke, Bente Kiens & John L Ivy (2004) Carbohydrates and fat for training and recovery, Journal of Sports Sciences, 22:1, 15-30, DOI: 10.1080/0264041031000140527
- Anvith, Panchumarthy & Sankar, Ravi. (2015). The Comprehensive Review on Fat-Soluble Vitamins. IOSR Journal Of Pharmacy, Volume 5, Issue 11, 12-28.
- Shenkin A. Micronutrients in health and disease. Postgrad Med J. 2006 Sep;82(971):559-67. doi: 10.1136/pgmj.2006.047670. PMID: 16954450; PMCID: PMC2585731.
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