How To Use If It Fits Your Macros (IIFYM) for Weight Loss

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Losing weight can seem like a roller coaster of emotions and struggles clouded by a haze of confusion. That is until you start using something like if it fits your macros, also known as IIFYM. This is a type of flexible dieting, and this article will go over what this type of lifestyle means and how you can use it to your advantage in order to lose weight and eat healthier.

Sticking to a restrictive diet (along with a calorie deficit) can be a challenge, and flexible dieting is supposed to make things easier.

What are Macronutrients?

Calories in food
The number of calories present in 1 gram of:

  • Fat: 9 calories
  • Protein: 4 calories
  • Carbohydrates: 4 calories

Macronutrients are nutrients required in large quantities (“macro” vs “micro”) and intake is measured in grams or ounces (there are 454 grams in a pound.)

This concept is a way of eating that allows you to add food to your daily meal plan based on how many macronutrients it provides, rather than counting calories, restricting foods, and having to follow a long list of rules for what you can and can not eat.

Macronutrients are the things that our body needs a lot of, and it includes proteins, carbohydrates, and fat. There is also something called micronutrients, and these encompass the things our bodies need in a much smaller amount. Micronutrients are things like vitamins and minerals – iron, magnesium, vitamin C, vitamin A, etc.

As far as macros go, each one contains a specific amount of calories, and this is the foundation for the eating style that you will be following. According to the USDA, there are four calories per gram of carbohydrate, four calories per gram of protein, and 9 calories per gram of fat.

As mentioned, IIFYM is considered a type of flexible dieting, which means that it allows you to eat the foods you want without regard to pre-set guidelines or rules to follow.

Think of it this way. If your macros dictate that you eat 100 grams of protein during the day, then that’s your goal no matter what. You can reach that goal by eating by eating all fish or chicken, or you can opt for a more conservative route and make protein and chia shakes in order to get to that 100 grams.

Or you can go dirty.

Hamburger and fries on a diet? Sure, as long as “it fits your macros”. Just realize you still need a calorie deficit to lose weight.

Hamburger and fries on a diet?  Only IIFYM!

How This Works for Weight Loss

When following this diet, it’s important to realize that calories are calories. Calories from one food source are no better than calories from a different food source – as far as the energy they provide to your body. The main thing you need to focus on is how those numbers add up to meet the macronutrients prescribed for your body type.

Weight loss comes from a calorie deficit. This means more calories are going out than what is coming in. Burn more than you eat.

To lose 1 pound of body fat you must have a caloric deficit of 3,600 calories. This can be accomplished by a daily caloric deficit. For example, by consuming 360 calories less than what you need, every day for 10 days you could expect to lose 1 pound.

Eating excess calories, regardless of the source, or failing to exercise will cause you to gain weight rather than lose it. This also relates to the concepts of BMR and TDEE.

Your BMR is your basal metabolic rate, or how many calories you would burn from just lying in bed all day.

Your TDEE is your total daily energy expenditure, which is the number of calories you burn from doing any type of activity. Most calculators take BMR into account.

This way of eating helps with weight loss when you consider the bigger picture. The flexibility it provides you means that you can eat just about anything at any event and not have to worry about messing up your entire day. It’s also easy to implement no matter what your food budget is or your dietary preferences are.

How to Plan or Calculate Your Macro Ratios

There are many different ways to structure your macro percentages, depending on what your overall goal is.

You can use this to your advantage by structuring your macro ratios according to weight loss, bodybuilding, or strength training. Those looking for weight loss should aim for a lower carb and higher protein ratio, while those looking to bulk up should try for a higher carb and moderate protein intake.

You can check out the article here to get a better understanding of this.

It’s even popular for “macro coaches” to provide advice over the internet on the ideal ratios. Honestly, it’s not that hard to figure out. We don’t recommend “macro coaching”.

Alcohol is not a macronutrient but does contain 7 calories per gram – so if you are trying to lose weight limiting alcohol intake is important.
Your macro planning should not include an alcohol category, in case that isn’t clear.

In addition to macro ratios, there is something called the thermic effect of protein. This can be described as the number of calories it takes to digest food. Protein can help you burn slightly more calories, making it a great macro to increase if weight loss is your goal.

Recommended “Macro calculator” websites has a great macro calculator.

As does

How to Count or Track your Macros

There are a couple different ways to meet your macros each day. The first is that you can purchase a food scale and weigh everything you eat. This is great if you meal prep a lot or if you want an exact measurement for the foods you’re eating. The other option is to check the food label. This gives a quick breakdown of the proteins, fat, and net carbs (total carbs with the fiber content subtracted.

Apps that are popular for dieters using IIFYM

If you are on the go a lot or just want an easier way to track your macros, then you should consider a mobile app or website to help you out. There are several that are free to use. Here are three suggestions for this.




Criticisms of IIFYM

One of the main things to watch out for if you decide to use this way of eating is that it has the potential to slightly encourage unhealthy eating practices. You will need to use a little common sense to overcome this. For example, while eating cheeseburgers and other fast food every day may indeed fit into your macro goals, it will have other damaging effects, such as high cholesterol and heart troubles.

Dietary fiber is important to good digestive health. Fiber is found in grains, fruits, vegetables, and seeds. It includes the parts of plant foods your body can’t digest or absorb. If you are eating a lot of highly processed foods you are not going to reach the recommended daily intake of fiber.

Additionally, there are micronutrients to think about. Micronutrients are the nutrients our bodies need in small (micro) quantities – and vitamins and minerals are the key examples. If you are eating a variety of diverse fruits and vegetables you will have a better profile of micronutrients compared to eating highly processed foods.

Additionally, you have to think about your glycemic index. This is the way that carbohydrates raise your blood sugar level. A calculated high carb level in your macros has the potential to be a very big obstacle if you have other health issues, like diabetes.


To summarize, this way of eating is a type of set it and forget it method. You calculate the amount of the macronutrients your body needs and eat up to those limits each day. This eliminates food restriction and is flexible, but can cause issues if not followed appropriately. Overall, this is a great lifestyle choice that is easy to implement and that works great for most lifestyles.

IIFYM can work with any food sources, and that makes it easy to maintain your normal social activities.

But it’s also not magic. As with all weight loss diets, it requires a caloric deficit.

Lastly, IIFYM doesn’t necessarily encourage healthy eating habits from the perspective of fiber, vitamins, minerals, etc.

You may also like to review our article on the Paleo diet or the keto diet – both of which take a very different approach to healthy eating.

Pizza on a diet? OK IIFYM - If It Fits Your Macros - a type of flexible dieting that is based on portions of macronutrients instead of food restrictions. You still need a caloric deficit.