Quick Easy Steps to Understanding Flexible Dieting (IIFYM)

It seems like every day, you hear about some sort of new diet that claims to be the ONLY way to lose fat or reach your goals. Some of these diets may require you make extreme changes to your diet like eating zero carbs while others have you eat primarily carbs. Some claim that to lose weight, you must restrict your calorie intake to unhealthy levels or that restricting one food group will be the driving force to reaching your goals. It seems people will follow any structure of dieting that claims to work even if it lacks any scientific evidence or success in practice.

Wouldn’t it be nice to stop following these obscene ideas and still reach your goals? Well, whether you’re training as a bodybuilder or just for better health, you have most likely heard or read about flexible dieting or the term IIFYM (if it fits your macros). This is a style of dieting that gives you the flexibility to operate through life’s obstacles and continue to reach your goals whether it me losing, gaining, or maintaining your weight. 

What is flexible dieting and IIFYM (if it fits your macros)?

To understand what flexible dieting is, it is first important to know some nutrition basics.

What are macro-nutrients?

Macro-nutrients are the nutrients that contain calories. These nutrients are the body’s primary source for energy and are needed for growth, metabolism, and other body functions.  

  • Carbohydrates
  • Protein
  • Fat

What are micro-nutrients?

Micro-nutrients do not contain calories and are needed in smaller amounts as compared to macro-nutrients. These are essential for good health and the function of overall bodily functions.

  • Vitamins
  • Minerals

Calories and Thermodynamics

Thermodynamics dictate that a calorie is a calorie regardless of the macronutrient composition of the diet.1

Flexible dieting is a scientific approach to dieting that allows you to stop dictating foods as clean and dirty and instead to focus on total caloric intake. Macro and micro-nutrient targets are set in order for you to achieve your desired body composition.

This style of dieting allows you to have a comfortable social life while still meeting your goals. Whether you’re a bodybuilder trying to cut down for competition or just the average person trying to lose a few pounds, this is a style of dieting that won’t make you lose your mind after the first week. You will have more freedom to fit “unhealthy”, “cheat” meals into your regular diet as long as you abide by your macronutrient intake.

The idea of flexible dieting is not for people to splurge on pop tarts and to have whey protein shakes as their only source of protein, but to instead present balance to your life while keeping healthy and sane.

How to Start

1.       Set caloric goals

Overall caloric intake is by far the most important number in meeting your goals. Although there is debate over macronutrient numbers, the number of calories you are consuming is the most important.

If your goal is to lose body fat, thermodynamics shows that you must consume a number of calories below which your maintenance caloric intake is. If your goal is to gain weight and muscle mass, you must consume a number of calories that is above your maintenance caloric intake.

There are various formulas to determine estimates of your maintenance caloric intake. However, it is important to understand that diet is highly individual. What I mean by this is that two people who are the same gender, weight, and height may have different maintenance caloric intake. It may take weeks or even months of experimenting with different base calories in order to find your maintenance number.

In order to set calories for your goal simply increase, decrease, or maintain these numbers.

2.       Set protein intake

Protein is the first macronutrient number that should be set. Protein is an essential nutrient important for repairing broken down tissue as well as the growth of new lean muscular tissue.

There is much debate over the amount of protein that you should consume, but a general consensus within the fitness community is 1 gram per pound of lean body mass.

3.       Set fat percentages

For most people, when they hear the word fat, they think to completely stay away from it. With all the non-fat foods being produced, many people begin to believe that any consumption of fat will result in weight gain. Fat does contain higher amounts of calories as compared to the other macronutrients; however, it is still a very important nutrient in your diet. Fats have many important functions including providing energy, building healthy cells, making hormones, and other bodily functions.

Dietary guidelines recommend about 15%-25% of your total calories to be fats.

4.       Account for micro-nutrients and fiber

Micronutrients are important. When the term IIFYM is used, many see it as a way to disregard micronutrients as a whole. Well, this is not the idea.

Vegetables, fruits, and animal protein foods contain an important variety of vitamins, minerals and antioxidants that you’re body needs to function properly.

One very important nutrient that many have begun to track along with the primary macronutrients is fiber.  Fiber is a special type of carbohydrate that is important in the digestion process. It is recommended to consume about 14 grams of fiber for every 1,000 calories of you’re diet.

How to log your macronutrients

In order to show you how to track your macronutrients, here’s an example.

Calories per macronutrient:

Protein: 4 calories per gram

Carbohydrate: 4 calories per gram

Fat: 9 calories per gram

Male: 180 lbs/22 years old/6’1”

Caloric intake goal: 2,400

Protein: 1 gram/lb = 180 g protein = 720 calories =30%

Fats: 20% = 480 calories = 53 g fats 

Carbohydrates: 1200 calories = 300 g carbohydrates = 50%

What to use to track? 

New phone apps have made it a heck of a lot easier to track macronutrients. Apps such as MyFitnessPal or SparkPeople allow you to enter the foods that you have eaten that day and automatically keep track of the macronutrients and other nutritional information. These apps are available on mobile phones, tablets, and computers making it easy to quickly enter in all of your foods and keep count of your macronutrients for the day.

When tracking foods and counting macronutrients, it is important to keep track of everything that you’re eating. You never really know how much you are eating unless you accurately keep track of it. Eventually, you will be able to eyeball serving size, but until then, weigh, measure, and accurately keep track of everything you consume.


1.       Diet takes time

Diets are highly individual and may take weeks or months to find out what works for you. Experiment with macronutrient percentages and caloric intake to meet your goals. Some people respond better to diets in high volumes of carbohydrates and some in high protein. It is important to make changes when necessary to meet your goals.

2.       Stop fretting over “clean” foods

Although “clean” foods are important for the micronutrients and fiber that they contain, there is no reason why you can’t fit pizza or ice cream into your diet once in a while as long as it’s in context. If you can add these “dirty” foods into your diet while abiding by you macronutrient numbers, you will still reach your goals.

3.       Protein, protein, protein

If you are looking to lose fat and retain lean muscle mass, protein intake is very beneficial. Especially if you are an athlete, be sure to do your best to meet your protein intake goals in order to improve performance and looks.