Flexible Diet: The Complete Guide

Flexible Diet
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A flexible diet has a lot of critics and even more supporters. But does it suit you? The guide contains all the important information with some numbers for a good start!

For decades, it all came down to the number of calories received per day. Stay in short supply, and in theory, you will lose weight. Create an excess of calories, and you gain mass. To some, such an approach brought results, but for many, it turned out to be insufficient, unsuccessful and, ultimately, a failure.

And then someone finally asked the question: “What if calories are just the beginning?”

As a result, a new principle of making a diet, the name of which is “flexible diet” or IIFYM (“If it fit your macros”), broke into the world of fitness. This concept has turned the usual restrictive approach upside down, focusing on monitoring the consumption of macronutrients. As long as you fit in certain numbers, theoretically there are no restrictions on the products you can eat.

Is a “flexible diet” an ideal concept with “anti-fool”? Of course no. Although the magical idea of ​​a flexible diet may seem simple, making it part of your lifestyle is not easy. You need to have deep knowledge about some of the key principles of dietology because it is very easy to make a mistake! But with proper application, it can be the fact that, unlike many diets, will help you consistently adhere to the planned plan for a long time.

If you are new to nutrition, or just look for new ideas, the information below will be useful for you. We will talk in detail about macronutrients, about possible proportions of BJU and, of course, about the IIFYM diet itself!

If it fits into your limit

Macronutrients, or abbreviated BJU, are the main nutrients: proteins, fats, and carbohydrates. Instead of throwing all the energy into counting calories or denigrating fats or carbohydrates, the “flexible diet” focuses on covering the daily needs of the body. With the right approach, it provides a steady intake of calories, but the sources of these calories can be represented by an infinite number of combinations.

At first glance, the concept may seem unnecessarily complex: “Why include three counters if you can use only one?” The fact is that after shifting the emphasis to individual BJU requirements (and to choose high-quality products), it will be easier for you to adapt the diet to your lifestyle, taste preferences and goals.

Imagine 2000 calories. It’s not that easy, right? You could get these calories from an infinite number of combinations of foods, both healthy and unhealthy. In the first case, 2000 calories would help you refuel for fantastic workouts, build muscle and feel full. In the second, you could have left you at the broken trough, with the usual jumps in blood sugar, an obscure head, and a shaky pace in the gym. In short, it’s not enough to count calories, you need to move to another level!

Macronutrient management is like budget planning. Instead of spending calories on anything, as long as this “stuff” fits into the total limit, you’ll have to manage a budget of three key currencies proteins, carbohydrates, and fats. If you want to spend the whole budget on pancakes for breakfast, go ahead, but remember that you still need to get a due portion of fats and proteins. Do not be surprised if by lunchtime you suddenly become tired. You have consumed all the carbohydrates, and now your fuel tanks are empty, although there is still a car and a small truck.

However, the beauty of the “flexible diet” is that from time to time you can deviate from the course, remaining within the budget, if you take into account errors in the diet in other meals. For example, if a dinner party is scheduled for a special occasion, it is enough to correct the morning and afternoon meals in order to enjoy the full evening.

Cover the rate of BJU

With proper use of “flexible diet” offers an excellent balance of stability and flexibility. Determine the daily rate of BJU (we will get to this soon), and use the right to choose from a variety of products to cover this need. In the end, you can get calories from anywhere, but you have to look for macronutrients in certain sources.

Build your day around these sources, and you will have room to maneuver when necessary.


Sources of protein. Egg whites, egg yolks, milk, cheese, yogurt, cottage cheese, chicken, turkey, pork, beef, fish, nuts, beans, peas, lentils, soybeans, and other legumes.

Biological role. Protein is a combination of amino acids necessary for recovery, muscle growth and regenerative processes throughout the body. But protein is not only biceps, but it is also a feeling of fullness, which is useful for exercising people who want to lose weight or gain muscle mass.


Sources of carbohydrates. Oatmeal, rice, bread, cereals, pasta, quinoa, potatoes, fruits, vegetables, chips, cookies, sweets.

Biological role. Carbohydrates – the main source of energy. This fuel is preferred by both the muscles and the brain.

There are two types of carbohydrates: simple and complex. Complex carbohydrates are absorbed slowly, and the foods in which they are contained usually have a darker color. They are full of vitamins and minerals, and due to the high content of fiber, they provide a steady flow of energy. Examples are oats, brown rice, starchy vegetables, and whole-grain bread.

Simple carbohydrates are absorbed very quickly, and the foods in which they are contained are usually lighter. Examples are white rice, white bread, pastries, and sweets.


Sources of fat. Olive oil, canola oil, coconut oil, natural peanut oil, and other peanut butter, avocado, almond, walnut, cashew, redfish, mackerel, egg yolks.

Biological role. Fats are essential nutrients involved in many physiological processes. They play an important role in cellular signaling systems and provide communication within the body. Fats allow the body to absorb vitamins and help maintain healthy hormonal levels. Not to mention the fact that they are tasty.

Unsaturated fats. They are usually called the “most beneficial” fats because they have a positive effect on the cardiovascular system, mental activity and memory.

Saturated fats. Participate in the synthesis of testosterone, optimize the production of other important hormones.

Trans fat They are often called “harmful” because they negatively destroy blood vessels and increase the risk of developing various metabolic disorders.

Flexible diet versus traditional diets

If you have gone through the complexities of traditional diets, it may be difficult to understand how a “flexible diet” differs from a free diet, but to lose weight, it is still important to maintain a calorie deficit, regardless of what products they come from. Let’s compare these two approaches.

Difference 1. Restrictions Policy

The principle of many traditional diets is based on a strict calculation of calories, a certain list of products, and sometimes a complete ban on a product or group of products (for example, a low-fat or low-carb diet is used for weight loss). This approach initially gives results, but often does not work in the long run.

Due to the feeling of being deprived and losing strength, the error in one meal turns into a day of permissiveness, which ultimately puts an end to all good intentions. A few weeks later, the person returns to the original body weight, and even sets a personal record. This is a vicious circle of many diets.

A “flexible diet” saves you from the fear that a product “does not fit into the limit”, and you can choose from a variety of foods. Instead of worrying about irregularities, you can regularly enjoy sweets, continuing to move towards your intended goal without feeling guilty. The whole thing in controlling the size of servings. It is still not easy to stick to a diet, and from time to time you may be overwhelmed by the feeling of hunger, but a balanced approach will make the process much more tolerable.

Difference 2. Performance in the gym

Anyone who has ever tried to train for wear on a calorie restricted diet — or during an extreme low-fat or low-carb diet — knows how hard it can be. Your workouts suffer greatly, as does the overall energy level. Of course, the dice press appears in the kitchen, but do not underestimate the importance of months of high-quality workouts. If you want to improve the composition of tissues in the long term, they can not be neglected! And extreme calorie restriction is unlikely to help you.

The “flexible diet” shifts the emphasis on the importance of each macronutrient, given its unique biological role. With the successful implementation of the principles of a flexible diet, you will have enough strength for very intensive training, even in the phase of losing weight, drying or working on the relief.

Difference 3. Social aspect

If you are on a diet with a specific list – implied or directly declared – of “prohibited” products, you know that even the mere thought of a cake can fill you with guilt. Too often, people give up slack, and then as punishment they starve themselves or eat very little. This is not a healthy or balanced approach.

Adhering to a flexible diet, you can avoid stress in such situations. You can get more or less certain nutrients than planned, at some meal. But do not forget that you still need to fit into the limit! This is a very flexible system, and you can adjust it to your lifestyle, as long as you continue to control calories and BJU.

This principle applies to dinners in the restaurant. People on diet restaurants often alarm, because it is difficult to control the size of servings and the method of cooking. Understandably, many restaurants will never be completely frank about calories and BJU, but if you don’t want to abandon the idea of ​​counting the share of macronutrients, simple math may be enough to make the right choice.

The positive side of the global problem of obesity is that today more than ever before many restaurants spread the nutritional value of food online, and in some of this information you can find out right on the spot. Examine the menu in advance and determine what will fit into your limit, or what you can afford. This will allow you to enjoy lunch without a headache about the accounting of calories and BZHU.

Difference 4. Scientific arguments in favor of a “flexible diet”

Many studies have shown how ineffective the traditional restrictive approach to diet can be, and statistics is the best proof of this. But the better diet IIFYM? It turned out that a study was conducted that compared the traditional approach with a flexible diet.

When comparing the two concepts, scientists have concluded that a restrictive diet increases the risk of a subsequent increase in BMI, deterioration of self-control and the development of mental disorders on the basis of food intake and weight gain. Consider it another victory flexible diet.

How to avoid flexible diet traps?

I am not going to protect all variations on a flexible diet. Many people misinterpret its principles and leave vivid proofs of their mistakes on Instagram. Because of this, the flexible diet has a reputation for “unhealthy”, although it definitely should not be so!

Error 1. Ignoring trace elements

Vitamins and minerals, also known as trace elements, are very important if, of course, you want your body to function as well as it looks. They are equally important for the training process and recovery! Unfortunately, many supporters of the IIFYM diet too often choose cakes instead of carrots.

Solution to the problem. Make a conscious decision to include in the diet a variety of nutrient-rich foods such as whole grains, fruits, and vegetables. They should be the rule, not the exception. Moreover, I insist that you should make a portion of non-starchy vegetables “voluntary” and forced at least three times a day.

Mistake 2. Lack of protein

Of course, occasionally fatty steaks and fried foods can appear on your menu, but you have to pay a high price in the form of calories for them. On the other hand, if you do not carefully select proteins of plant origin, you may miss the key essential amino acids necessary for optimal muscle growth and recovery.

Solution to the problem. Find out what is the difference between high-grade and defective protein; low-quality protein sources should not be counted in total protein. I like the peanut butter example. There can be 8 grams of protein per serving, but this is a defective protein, that is, it lacks one or more essential amino acids. Unless you spread it on toast or combine it with high-grade protein (any source of animal protein), you should consider it only as fat. Save protein digits for non-fat high-quality sources. They are rich in nutrients and support growth, muscle recovery and a feeling of fullness without extra calories.

If you are a vegetarian, be sure to combine different sources of protein, such as rice and beans, or choose high-grade vegetable proteins, such as quinoa or soy, to get enough essential amino acids every day.

Mistake 3. Horrible selection of carbohydrates.

By analogy with the neglect of trace elements, many prefer sweets to natural, rich in fiber, but not so tasty foods. I’m talking about Sneakers instead of oatmeal or Skittles instead of an apple. Both are carbohydrates, but you will definitely feel the difference: a short burst of energy and a subsequent energy crisis. As a result, it is difficult not only to train but to work productively throughout the day.

Solution to the problem. Do not think that the “flexible diet” allows you to eat as in childhood. Periodically, you can treat yourself to chips, cookies, pastries or sweets, but this is still a delicacy and not the basis of the diet. Plan your meals in advance and make them the basis of fiber-rich sources of carbohydrates, such as oatmeal, brown rice and other foods that provide a constant flow of energy. Not all carbohydrates are the same! The source of carbohydrates, the timing, and quantity-all of this have a big impact on energy levels, performance, and recovery.

Mistake 4. Lack of essential fats.

Pizza, hot dogs and ice cream – this is very tasty, but if this is the only source of fat in your diet, you have problems. There are a lot of fats in these products, but they practically do not contain healthy fats, which strengthen the heart and blood vessels, reduce cholesterol levels and help to improve the composition of tissues.

Solution to the problem. Treat treats like treats. At other times, lean on nuts, seeds, egg yolks, vegetable oils, fish oil and avocados, which will provide you with the optimal combination of fats that are good for the heart and speed up recovery.

Calculation BZHU for beginners

Got to what you were waiting with so much impatience! If you are interested in the concept of a flexible diet, but you did not know where to start, start from here. Yes, at first you will count calories – I hope that by this moment it is clear that this is not the end! – and then try one of several time-tested proportion of BJU.

Step 1. Determine your calorie needs.

Just enter the basic information in the online calorie calculator, and you will know approximately how much energy you need to maintain your body weight. Depending on whether you plan to gain or lose weight, add or subtract 300-700 calories from the resulting figure.

This is an important step and should not be missed. Remember that the calorie calculator only calculates your daily energy requirement. If you are not used to estimating the calorie content of your diet, I recommend starting with the resulting figure, assess the dynamics of changes in body weight after 5-10 days, and then cut or add calories to create the necessary deficit or excess energy.

Step 2. Choose the proportion of macronutrients.

The proportion of BJU is the percentage of calories that each macronutrient accounts for. Usually indicated in the following order: carbohydrates/proteins/fats. Here are three classic options:

In the bodybuilding example, 40% of calories comes from carbohydrates, 40% comes from proteins, and 20% remains to fats.

Perhaps by the end of the year, your proportion will change significantly, but these figures will be an excellent starting point. Choose the ratio of BJU and stick to it. Very soon you will learn how to quickly count macronutrients, without guesswork and stress from analyzing each gram.

Step 3. Translate BJU in calories and grams

Calculate the energy value of the diet according to the percentage of your proportion, and check that it corresponds to 100%. So you will find out the total calories from carbohydrates, proteins, and fats. Let’s continue to use as an example the diet of a bodybuilder with a daily rate of 2500 calories:

Macronutrient% of consumptionCalories

Divide the total number of calories from each nutrient by the number of calories contained in one gram. This will tell you how much protein, fat, and carbohydrates should be on your menu.

MacronutrientCaloriesCalories per gramTotal grams

Round each digit to the nearest gram (or, to make it easier to remember, round up to five grams). This is your daily need for BZHU.

There is no “wrong” proportion of BJU. Ultimately, you will come to the most comfortable option for yourself, which can be maintained in the long run. As long as you maintain a shortage or an excess of calories, you are moving in the right direction. Your proportion affects your well-being and performance, as well as the speed of approaching your goals.

IIFYM Advanced Diet

The longer you exercise and keep records of food, the more you will learn about how your body reacts to a certain level of fat and carbohydrates. However, if you want to find the proportion of BJU that suits your training goals and taste preferences, I recommend starting with protein and then working on finding a balance between the two remaining macronutrients. This is what this process looks like:

  • Step 1: Determine your daily calorie intake for your goals.
  • Step 2: Try to get 2 grams of protein per 1 kg of body weight (or select your amount of protein).
  • Step 3: Get the missing calories from carbohydrates and fats. Some people prefer a higher level of carbohydrates, others – a menu with a high content of fat and a moderate proportion of carbohydrates.

I will give two examples based on a diet with 2,100 calories for a woman weighing 70 kg:

High carbohydrate approach

  • Carbohydrates: 300 grams
  • Protein: 145 grams
  • Fat: 36 grams

Medium Fat Menus

  • Carbohydrates: 200 grams
  • Protein: 145 grams
  • Fat: 80 grams

Frequently asked questions about a flexible diet

Why not just count calories?

Consider calories when choosing healthy foods, and the final balance will definitely work! As long as you maintain the necessary shortage or excess, your weight will change. However, counting BJU will help to focus on each nutrient, which means that it will be easier to adjust the proportion to individual training goals and features of training.

Do as you see fit, but do not try to drastically reduce the calorie intake. For many people, excessive concern about the caloric content of the menu leads to the same old trap: they feel left out, exhausted and tired. I am sure that such a scenario is not in your plans for improving the diet.

Do I need 100% accuracy?

When it comes to calories, absolute accuracy is nothing more than a myth. Unless you are preparing to enter Olympia, do not bother with trifles. Plus or minus 10 grams of protein and carbohydrates is not a problem. This will give you more flexibility and eliminate the need to carefully analyze each meal. If your goal is 250 grams of carbohydrates, it is enough to stay in the range of 240-260 grams. The difference does not exceed 40 calories in any direction. And there is nothing to worry about.

On the other hand, fats contain more than two times more calories than proteins and carbohydrates, namely 9 calories per gram versus 4. To minimize the risk of excess calories, try to stay within 5 grams of the intended goal. If your goal is 60 grams, everything within 55-65 grams will do. The final fluctuations within 45 calories can also be called minimal.

How do you recommend to count BZHU?

Consider BZHU as you are comfortable. Mobile apps can be a great help, as many of them allow you to keep track of your diet on the go. Most of them already have a huge database of nutrients and products that allow you to find almost every product. Some even have a barcode scanner that helps to keep track of every product you eat.

In my menu, three servings of non-starchy vegetables per day. Should they be counted?

Most vegetables contain very few calories (with the exception of starchy vegetables, such as peas, potatoes and corn), and many are against their inclusion in BJU. However, they still have calories and carbohydrates, so there are arguments for the opposite point of view.

My recommendation is to include non-starchy vegetables in at least three meals. Do not count this amount, and make efforts so that vegetables are present at each meal.

If you have more than one serving per meal, consider the carbohydrates from the following portions to control the total calories. For example, in 1 cup of zucchini 7 grams of carbohydrates. If you are planning 3 servings per meal, count the carbohydrates from the second and third portions only. In this example, you would consider 14 grams of carbohydrate per meal.

Should BZHU be the same every day?

Here everything is your choice. To make the preparation and accounting of food as simple as possible, many experts recommend sticking to the same proportion of BJU, regardless of having a workout that day. Of course, it can save you a couple of minutes, but on the other hand, your calorie needs are different on rest days and on hard training days. Do you need much time to weigh another 100 grams of brown rice? Personally, I think not.

You probably do not need specific proportions of BJU for each day of the week, but I recommend varying them on training days and rest days. In those days when you do not exercise, you do not have such a high need for carbohydrates, because you spend a lot less calories. Cutting carbohydrates will help lead to a common denominator nutrition and exercise, which is especially important during weight loss and drying. I recommend reducing the proportion of carbohydrates by 30-50%, and leaving proteins and fats at the same level.

An example of a diet on a training day

  • Carbohydrates: 250 grams
  • Proteins: 185 grams
  • Fat: 70 grams
  • Calories: 2370

Sample rest day diet

  • Carbohydrates: 125 grams
  • Proteins: 185 grams
  • Fat: 70 grams
  • Calories: 1870

If I got the BZHU norm, do I need to “get” the missing calories?

This happens all the time. Say, the daily need for calories is 2500, and you got the standard BJU with a deficit of 110 calories. Do not worry about the “supplementation” of these extra calories. Focus on BJU, and calories will equalize over time.

The choice of foods you make every day affects the total number of calories, and this amount differs on different days. For example, a serving of olive oil will give you 15 grams of fat, and 15 grams of peanut oil will also give you minimal amounts of protein and carbohydrates and about 80 extra calories. The difference in calories over time is trimmed when you include a wide range of foods in your diet.

In reality, today’s insignificant deficit may be balanced by tomorrow’s slight excess. No need to “get” the missing calories. It is also worthwhile to relate to a slight excess of the planned calorie limit.

Can I eat forbidden food?

One of the main advantages of a “flexible diet” is that you can eat delicious combinations of nutrient-rich foods and your favorite delicacies. Formally, you can enjoy a piece of cake or a slice of chocolate every day.

However, from time to time everyone needs a psychological respite, during which you can not turn on the counters. For optimal progress – especially at the stage of losing weight – it is better to limit such “free meals” to one in a couple of weeks or one in a month.

This may sound like a restriction, but remember that you can eat anything every day as long as you watch the portion sizes. And it is worth a lot!

I am confident in my original BJU and want to aim at a set / weight reduction. What pace to move forward?

Regardless of whether you want to gain or lose weight, your goal should be to change body weight by no more than 1% of the initial weight per week so that changes in the composition of the tissues are optimal.

This means that a 75-kg woman who wants to lose weight should strive to lose no more than 750 grams per week to minimize the risk of muscle loss. An 80-kg man who wants to gain weight should, by analogy, strive to gain no more than 800 grams per week in order to minimize the gain of fat mass.

Keeping this information in mind, as soon as the dynamics of change in body weight begins to slip, make adjustments of 300-500 calories to keep moving in the chosen direction. In most cases, the best approach is to maintain protein intake at the same level (provided that it is sufficient) and manipulate carbohydrates and fats in order to slightly change calorie content.

The rest is your choice!

The “flexible diet” is not a strict system without the right to make a mistake, like the Atkins diet. This is a personalized approach that is very popular today, and there are as many ways to approach dieting as there are products on the supermarket shelves.

I’m sure you can get lost in the wilds of analysis and calculations, but this approach should be fun! Keep this in mind, do not forget that you must be honest and conscientiously keep records of calories and BZHU, and you will find yourself on the road to success. If you have any questions, or you have a successful experience in applying the IIFYM diet, share it in the comments!

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