If It Fits Your Macros – IIFYM Ultimate Guide


What is If It Fits Your Macros?

If It Fits Your Macros, or IIFYM for short, is basically a diet plan that allows you to eat whatever you want as long as you meet your daily target for each macro. So, what is a macro? Macro is short for macronutrient. All foods are made of macronutrients, micronutrients, and water.

  • Macronutrients are fat, protein, and carbohydrates. These nutrients provide energy through calories and are necessary for growth, maintenance, and repair of our bodies. Each macronutrient provides a certain amount of calories per gram. Fat has nine calories per gram while protein and carbohydrates each have four calories per gram.
  • Micronutrients are vitamins and minerals. They do not add calories to food, but they also help with growth, repair, and maintenance. There are 13 essential vitamins and 16 essential minerals.
  • Water is vitally important. It has many roles in the body, including regulating temperature, keeping blood volume consistent, carrying nutrients through the body, and lubricating and cushioning joints and organs.

How was IIFYM started?

The If It Fits Your Macros diet is also known as flexible dieting or eating dirty (as opposed to eating clean). It was developed by bodybuilders who got tired of eating their traditional chicken, rice, and spinach every day. Bodybuilders often follow a diet consisting of certain percentages of each nutrient. The IIFYM diet gave them a way to add variety to their diets while still eating the right amounts of each macronutrient.

An example of a typical diet that bodybuilders follow is 30 percent protein, 20 percent fat, and 50 percent carbohydrate. Eating more protein is beneficial for body builders because they can add muscle mass while managing hunger. Protein helps us feel fuller and avoid overeating. To determine the amounts of each macronutrient to eat, bodybuilders would first need to figure out how many calories per day they’re going to eat. For example, a male bodybuilder may eat 3,000 calories per day. Then the amounts of each nutrient needed are calculated. He would need to eat:

  • 30% of 3,000 calories = 900 calories

900 calories / 4 calories per gram = 225 grams of protein

  • 20% of 3,000 calories = 600 calories

600 calories / 9 calories per gram = 67 grams of fat

  • 50% of 3,000 calories = 1,500 calories

1,500 calories / 4 calories per gram = 375 grams of carbohydrate

if-it-fits-your-macros-eat-itThe theory of the diet is that it doesn’t matter if the 225 grams of protein, 67 grams of fat, and 375 grams of carbohydrate come from healthy or unhealthy sources. The protein could come from low-fat turkey, or it could come from bacon. The carbohydrates could come from whole-grain bread or from pastries. As long as the target amounts are reached, this person should be able to reach their goal, whether it’s weight loss or increased muscle mass.

How does If It Fits Your Macros work?

IIFYM works because structuring your diet by percentages of each macronutrient is an effective way to lose weight or increase muscle mass. There are many different ways that diets can be structured in terms of protein, fat, and carbohydrates. Endurance athletes may need to eat diets that are higher in carbohydrates, while strength athletes may eat diets higher in protein. Eating a higher protein diet can also be helpful for weight loss. Before deciding how much of each nutrient to eat, it’s helpful to have an overview of what the macronutrients are and what they each do in the body.

  • Protein is also referred to as amino acids. Protein is used in all cells of the body for growth, maintenance, and repair. Protein has other roles as well. Some proteins act as enzymes, helping with digestion and other reactions in the body. Other proteins are hormones, helping regulate metabolism and electrolyte balance. Protein also forms antibodies that defend the body against viruses like colds and flu. In addition, protein helps regulate fluid balance and acid-base balance in the body.
  • Fat is also referred to as lipids. The different types of fat are triglycerides, phospholipids, and sterols. Fat also has many important functions in the body. Fat provides energy, protects the body against temperature extremes, cushions the vital organs, and sustains cell membranes.  Certain types of fat have other functions too. Omega-3 and omega-6 fatty acids are essential fatty acids, meaning the body can’t make them on its own. These fatty acids help prevent heart disease and may also prevent depression. Cholesterol is also important. It’s used in the body to make hormones, including testosterone and cortisol.
  • Carbohydrates include sugars, starches, and fibers. Sugars are known as simple carbohydrates, while starches and fibers are complex carbohydrates. The main role of carbohydrates is to fuel the body, including the brain and muscles.

Two other food components should be mentioned even though they aren’t macronutrients. Alcohol also provides energy to the body through calories. There are seven calories per gram of alcohol. However, alcohol isn’t considered a macronutrient since it’s harmful to the body. Alcohol has a negative effect on growth, maintenance, and repair of the body’s tissues. It’s basically a poison to the body that it has to work to get rid of. If you do drink alcohol, take into account the extra calories that it will add to your diet. You’ll still want to include the amounts of protein, fat, and carbohydrates that you’ve decided on, but your total calories for the day will end up being higher after you add in the calories from the alcohol.

Fiber is a type of carbohydrate, but some people consider it almost a separate nutrient. It doesn’t contain calories, but it does have an important role in the body. It prevents constipation by keeping more moisture in stools and adding weight to stools to reduce the amount of time they spend in the colon. Fiber also makes us feel fuller, so we end up eating less. Foods that contain fiber also take longer to chew, so the body gets the signal that it’s full before you eat too much.

40-40-20-macros-iifymOn the IIFYM diet, you won’t count the amount of fiber you eat. But if you’re trying to lose weight, it’s a good idea to think about including lots of high fiber foods, like fruits, vegetables, and whole grains. Most Americans don’t get enough fiber – men need 38 grams per day, and women need 25. On average, Americans only get 15 grams a day.

The diet recommended by the United States Institute of Medicine is 10 to 35 percent protein, 20 to 35 percent fat, and 45 to 65 percent carbohydrate. So, there is a wide range of ratios that you can eat to keep your body healthy. It’s important to remember that all the nutrients are important, so you don’t want to totally eliminate any of them from your diet. For example, if you don’t eat enough carbohydrates and fat, your body will have to convert protein into energy. It does this by breaking down protein in the muscles, and you don’t want to lose muscle.

How can you use IIFYM to achieve your goals?

Depending on your goals, there are different nutrient ratios you can follow to help you achieve results. A high protein diet like the example above (30 percent protein, 20 percent fat, and 50 percent carbohydrates) can be helpful for those looking to lose weight and gain muscle. There are many benefits to eating enough protein. Protein helps us maintain and build muscle and keep cells healthy. Protein also keeps you feeling full longer than carbohydrate or fat. Eating protein throughout the day is a good way to manage your appetite and prevent overeating.

Endurance athletes may want to follow a diet that’s higher in carbohydrates. Carbohydrates are the main fuel used for endurance exercise, like running, biking, and long distance swimming. The body can’t store carbohydrates in large amounts, so it needs be consumed throughout the day when training for endurance events. A sample diet for an endurance athlete may be 15 percent protein, 20 percent fat, and 65 percent carbohydrate.

The first step in using the IIFYM diet is determining how many calories per day you need to eat. The number of calories will depend on your age, gender, and activity level. The only exact way to calculate how many calories you need is to go to an exercise physiology laboratory and have your basal metabolic rate tested. For most people it’s fine to use an estimate, and there are many ways of estimating how many calories you need. The USDA MyPlate website can help you estimate how many calories you need per day. Another good way to start is to multiply your weight (in pounds) by your activity factor. Use this table to find your activity factor:

How much do you exercise? Activity factor
Almost never


Lightly, 1-3 days a week


Moderately, 3-5 days a week


Vigorously, 6-7 days a week


Vigorously, 7 days a week, + physical job



So if you weigh 140 pounds and train every day, you would multiply your weight by 17 and come up with 2380 calories. This is approximately how many calories you should eat every day to maintain your current weight.

Losing weight

iifym-dietIf you want to lose weight, you’ll need to eat fewer calories. Don’t cut too many calories, or your body will go into starvation mode and slow down your metabolism to protect itself. If this happens, you won’t lose weight. You want to keep your metabolism high through eating close to the amount you need and maintaining your muscle mass. The more muscle you have, the higher your metabolism will be.

Decreasing the amount of calories you eat by 300 to 500 per day is a safe amount. It should be enough to get results but not enough that your metabolism slows down. Cutting 500 calories per day will result in a weight loss of about one pound per week, which is safe and can be maintained. 500 calories x 7 days = 3,500 calories, which is equal to one pound.

In the example of someone who needs 2380 calories and wants to lose weight, they could try to cut 380 calories per day to come out with an even 2000 calories per day. After deciding to eat 2000 calories per day, the next step is to think about your goals and choose your nutrient ratios. Eating at least 30 percent protein has been shown to help people lose weight, as it decreases hunger. Using the ratios 30 percent protein, 20 percent fat, and 50 percent carbohydrates works well for losing weight as well as gaining muscle.

Remember that the amount of calories you decide to eat is just an estimate, and it may need to be adjusted. Try it for a couple weeks and then make adjustments if needed. If you’re not losing any weight, try eating fewer calories. If you’re hungry all the time and sticking to your diet but still not losing weight, you may not be eating enough calories. Try increasing the amount and see how it works for you.

Gaining lean muscle

If your goal is to gain muscle but not to lose weight, follow the above activity factor chart to estimate how many calories you need per day. Then you’ll actually need to add calories to this total if you want to gain muscle weight. Adding about 300 calories per day is recommended to ensure the extra calories help build muscle but not gain fat. Remember, eating too much of any nutrient will result in it being converted to fat and stored in the body in that form. On days that you don’t lift weights, go back to your base number of calories per day, as you won’t need to add the 300 calories.

iifym-muscleNext, choose your macronutrient ratio. For bodybuilding, the following ranges of nutrients are usually used:

  • 25-35 percent protein
  • 40-60 percent carbohydrates
  • 15-25 percent fat

Choose a nutrient ratio to start with, making sure that the percent of each nutrient adds up to 100. You can experiment and find which ratio works the best for you. The ratios you use can also depend on what phase of training you’re in, so a personal trainer or dietician may be able to help you set your ratios. And again, remember that the amount of calories you decided to use is just an estimate, so make adjustments as needed.

Improving performance in endurance sports

Some endurance athletes may not eat enough carbohydrates for optimal performance. The IIFYM diet can also be useful for making sure to get enough carbohydrates to fuel endurance workouts. First, estimate how many calories you need per day. You won’t need to add or subtract to that number if you’re trying to maintain weight and improve performance. The sample diet suggested above of 15 percent protein, 20 percent fat, and 65 percent carbohydrate may be beneficial. Again, adjust the amount of calories you eat as needed. They also may need to be adjusted on a daily basis depending on how long each day’s workout is.

Tracking your nutrient ratios

Now that you know how many calories per day to eat and how much of each nutrient to eat, calculate the grams of each nutrient you’ll need. Take your total calories for the day, multiply by the percentages of each nutrient, and then divide by calories per gram. You can use the example in the beginning and plug in your own numbers.

You’ll need a way to keep track of everything you eat during the day and how many grams it contains of each nutrient. There are different nutrition apps or websites you can use to track this for you. My Fitness Pal is one example that can be helpful for following If It Fits Your Macros. Or, you can go the old-fashioned way by carrying around a notebook and writing down everything you eat. Choose whatever is most convenient for you, as a key to this diet is recording everything you eat to meet your selected ratios.

Throughout the day, look at the nutrition labels of the food you eat to find the grams of each nutrient. If the food you’re eating doesn’t have a nutrition label, use a nutrition app or a nutrition website to look up the nutrition facts. You’ll also need to make sure you know exactly how much of each food you’re eating. Processed foods will be easier, as you can eat a premeasured amount and use the nutrition information on the label. Unprocessed or natural foods will take a bit more work. You’ll need to have a food scale to measure out portions of food you eat. Measuring cups will also be helpful.

As you record or track what you eat, pay attention to the ratios throughout the day. Then you can make adjustments as needed and make sure that your dinner or last meal of the day has the right amount of each nutrient for you to reach your daily targets. If you don’t hit them exactly, don’t worry – it’s more important to have a cumulative effect of being close to your goals every day.

What should you eat?

pizza-dietThe nice part about IIFYM is that you can choose to eat whatever you want. However, you’ll find that it’s hard to meet your ratios if you eat all “junk food” or unhealthy food. For example, if you want to eat pizza, you can. An average medium slice of pepperoni pizza has 10 grams of protein, 13 grams of fat, and 26 grams of carbohydrate. You could probably eat one slice and still meet your daily nutrient goals.

But, if you eat three slices of pizza, you’re up to 39 grams of fat. If you’re on a 2000 calorie a day diet with 20 percent calories from fat, your daily goal for fat is 44 grams, so you would have almost reached it with the pizza alone. After you eat the three slices of pizza, it will be hard to limit yourself to only five grams of fat for the rest of the day. Many foods that are high in protein, like nuts and some types of meat, also contain fat, so it will be hard to eat enough protein without also consuming some fat.

Overall, you’ll want to choose nutrient-dense, healthy foods for most of the day, and eat smaller amounts of the less nutrient dense foods. Good choices include fruits and vegetables, lean meat, low-fat dairy, and whole grains. By eating more nutrient-dense foods, you’ll get the nutrients that you need (including important vitamins and minerals) and feel full and satisfied. Select natural foods over processed foods, and choose foods without much added salt, added sugar, or added fat.

Traditional “clean” foods eaten by bodybuilders include whole grains like rice, rice cakes, and oats or oatmeal. Favorite high protein foods for bodybuilders are lean chicken, turkey, and fish, egg whites, and protein shakes. Vegetables like spinach and broccoli are also commonly eaten. But, these aren’t the only foods you can eat, and the more variety you have, the better. Some more good choices from each food group are:

  • Fruits: Any fruits are good! They are natural sources of carbohydrates. Fruits are also naturally sweet, making them a good low-calorie way to sweeten other foods without adding sugar. Bananas and other fruits are a great addition to smoothies made with yogurt, protein powder, and maybe some spinach too.
  • Vegetables: All vegetables are good too. Vegetables are also a natural source of carbohydrates. Some vegetables, like potatoes and sweet potatoes, have more protein than other vegetables, but they’re all healthy and nutrient-packed. Some vegetables, like avocados and olives, also contain some healthy fat.
  • Protein: Chicken and turkey without skin are good, low-fat choices, as are fish and shellfish. Baking, grilling, and broiling are good options for cooking without adding too much fat. Lean and extra lean beef is also a good option. Lean pork, venison, and tofu are also good. Egg whites or whole eggs are healthy sources of protein too. Nuts and seeds also contain protein; try pumpkin or sunflower seeds without added salt. Finally, beans, peas, and lentils without fat added are great sources of protein too.
  • Dairy: Milk, yogurt, and cheese provide protein, carbohydrates, and fat. Try fat free or one percent milk to avoid too much fat. Unsweetened soy, almond, and rice “milks” are also good options. They have varying amounts of protein, so check the labels and find one that meets your needs. Fat-free or low-fat yogurt are good choices. For cheese, low-fat or part skim cheese is best. String cheese and cottage cheese are good options.
  • Grains: Any whole grain foods are good. Try a variety of grains, like wheat, bulgur, barley, and rye. Air-popped popcorn is a good whole-grain snack.
  • Oils: Oils aren’t actually a food group, but they are essential. Most people get enough oil from foods they eat in the other food groups. Healthy sources of oils include nuts, fish, and olive oil.

As long as you eat these foods most often and eat the less healthy foods less often, you’ll be able to meet your macronutrient ratios. The USDA MyPlate website has more ideas for healthy choices from each food group. When planning what foods to eat, also remember that most foods contain more than one macronutrient. For example, bread is commonly thought of as a carbohydrate food, but it also contains small amounts of fat and protein. However, there are some foods that only contain one macronutrient. Sugar is a good example – it’s all carbohydrate. Keep this in mind when choosing foods. They probably contain more than one macronutrient, so make sure to read the label first.

If you go out to eat, it can be hard to know exactly how much you’re eating at its nutrition content. If you can, look up the restaurant’s nutrition information before you go. You may be able to pick out dishes you can order that will still meet your nutritional needs. If you can’t find information ahead of time, you may want to eat only a small meal at the restaurant. Try to estimate how much of each dish you’re eating. Then when you get home you can look up the nutrition information of each food and record it. This way you hopefully won’t go over your target amounts for each macro, and you can eat more at home if you didn’t get enough.

Eating Enough Protein

If you’re following a diet with a higher ratio of protein, there are lots of different ways to add protein to your diet without adding too much fat or carbohydrates. Meat is a common source of protein, but you can also get protein from nuts, beans, seeds, eggs, cheese, milk, and soy foods. Protein powder can also be a good way to add protein.  Including a variety of these foods is a good way to increase your protein intake. Here are some ideas for each meal of the day.

  • iifym-mealBreakfast: Greek yogurt is a good source of protein. Try it with healthy granola (try to find it without added sugar) and berries. Add in some almond slivers for more protein. Eggs are also a great source of protein. Stir in some black beans and cheese for a tasty high-protein breakfast.
  • Lunch: A traditional lunch of a sandwich and salad may not give you enough protein. Try adding more lean meat and only using one slice of bread. You can also eat soup or chili with beans as a side, or add almonds or cashews to your salad.
  • Snacks: Nuts and nut butters are good high-protein snacks that can help control your appetite between meals. Try combining the high-protein food with food from another food group for a balanced snack. For example, try an apple with peanut butter. Hard boiled eggs are also a good snack and one that’s easy to make ahead of time and take with you to work. Protein powder is also a quick and easy snack to have when you’re on the go, especially after workouts.
  • Dinner: Include lean meat, fish, or poultry for a good serving of protein. Tofu can also be a good choice if you don’t eat meat. Cottage cheese is also high in protein, and with a little fruit mixed in it could be a good addition to dinner.

What are the benefits of If It Fits Your Macros?

Just like with most diets, there are some pros and cons to IIFYM. First, the pros:

  • Flexibility: It’s hard to eat perfect 100 percent of the time. If you can do it, great. But, for many of us, we can only eat perfectly for so long before we give in to cravings and have a day where we “blow our diet” and eat lots of unhealthy foods. The goal of If It Fits Your Macros is to prevent that. By allowing some unhealthy foods each day, you’ll be more satisfied and never go totally off your diet.
  • Calories in, calories out: The main factor in weight loss is expending more calories than you eat. A consistent negative calorie balance will result in weight loss. Since the first step in following If It Fits Your Macros is determining how many calories you’ll eat, as long as you stick to this you’ll lose weight.
  • High protein: Although the amount of calories you eat is the main factor is weight loss, what you eat also has an effect. There’s evidence that a high protein diet is helpful for weight loss since protein keeps you feeling full longer and prevents overeating. Since you can set up your nutrient ratios any way you like in the If It Fits Your Macros diet, you can make sure to get enough protein.
  • High quality foods: To make this diet work, you’ll need to eat mostly high-quality, nutrient dense foods. As described above in the pizza example, it just doesn’t work to eat mainly unhealthy foods and still meet your macros. Eating mostly healthy foods ensures that you can fuel your body for workouts. It also helps you get enough vitamins and minerals that you need for optimal health.

The cons of IIFYM:

  • Lots of work: It’s hard work to track everything you eat. Weighting or measuring out portions of food can get tiring. It’s especially tough if you’re not at your own home or you go out to eat. Tracking everything you eat can also be difficult. These reasons may make the diet hard to follow long-term.
  • Allows “junk” food: Some people feel that IIFYM is inferior to “clean eating” diets that allow only healthy, nutrient-dense foods. However, eating totally healthy all the time is difficult for most people, so If It Fits Your Macros is a good approach that allows for small amounts of unhealthy foods.

Overall, IIFYM is a healthy approach to eating. The only real drawback is the time and effort it takes to measure our portions of food, record everything that’s eaten, and calculate macros throughout the day to reach your targets. If this is an issue for you, one option to solve this problem would be to only calculate your nutrient ratios some days.

For example, maybe for the first couple weeks on this diet you would calculate your nutrient ratios every day. But after you get used to doing this, you’ll start to have a good idea of what to eat and how much of it to eat. Then you could go without recording your food every day. You may want to still do the calculations every other day or every third day to stay on track. If you like this approach, try it and see if you’re able to eat the same on days you’re recording as days you’re not. Eventually, you may be able to go without recording at all as long as you’re still meeting your goal, whether it’s weight loss or increased muscle.

If It Fits Your Macros can be a safe, healthy way to lose weight. Make sure that you still eat enough calories per day and that you don’t get too low on any one macronutrient, as they’re all important. Monitor your progress and make adjustments as needed. You’ll also need to change the amount of calories you need as you gain weight from muscle mass or lose weight. Talk to a dietician if you want more help in figuring out how many calories to eat and how much to eat of each macronutrient. Enjoy your food, and enjoy the results of this diet!


  1. Right now I’m feeling totally lost as how to meet my macro requirements,because its 1114 . I’m 5’6.5″ and 130 lbs. I used macrofit to calculate my numbers and my goal was to lose weight ( I choose the faster weight loss option). Also I’m a pescatarian and I don’t eat eggs, drink milk , or any other animal products other than fish. This is making it harder. Help me please.