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Body recomposition and how to evaluate your progress?

What is a healthy ratio of muscle mass to body fat? How does it affect our appearance and how to evaluate it?

Most people who are trying to lose weight want not only to reduce their weight but also to get a fit and beautiful body.

However, reducing body fat alone is unlikely to succeed because as the fat layer thins, your real body (what lies beneath the fat layer) will become more and more visible.

And if your muscles are weak and undeveloped – of course, you will look slimmer, but not as fit and beautiful as you could be. Subjectively, of course, but look at this photo - they both have the same weight, the difference is only in the ratio of fat and muscle.

Body recomposition

Seems unbelievable? But it is because 1 kilogram of fat takes up more space than 1 kilogram of muscle.

The muscles are tighter. The average fat density is 0.9 g/ml, but muscle density is 1.1 g/ml. So - 1 liter of muscle weighs about 1.1 kg, and 1 liter of fat weighs about 0.9 kg.

Respectively – 1 kilogram of fat takes up about 20 percent more space than 1 kilogram of muscle.

Why am I telling this?

Because most people who want to lose weight consider their body weight to be the most important indicator of their progress, but as you can see, two different people with exactly the same weight can look very different.

Body recomposition

Weight is also not a clear indicator of what health risks you may face, as it does not show the ratio of fat mass to the rest of the body weight.

Conclusion - in order to get a beautiful, fit and strong body, while reducing the amount of fat, it is necessary to increase the muscle mass at the same time.

This approach also has additional bonuses – as your muscle mass increases, so will your strength and the number of calories you burn during the day. Respectively - you will also be able to eat more 😊.

Read about how to speed up metabolism HERE.


What is body recomposition?

Body recomposition is the process of reducing body fat mass while simultaneously increasing lean body mass.

Lean body mass includes muscles, bones, ligaments, tendons, organs, other tissues, and water – everything that is not body fat.

Body recomposition can be done in three ways:

  1. By reducing body fat mass and maintaining lean body mass. For example – "eating less";
  2. Maintaining body fat mass and increasing lean body mass. For example – increasing physical activity;
  3. By reducing body fat mass and increasing lean body mass. For example, starting strength training and following a diet designed for this purpose.

Usually, the term "body recomposition" refers to the third method — reducing fat mass while increasing muscle mass.


Body composition and weight loss

When losing weight, body weight is usually used as the main measure of progress. If it decreases, it is concluded that the "mission" is successful.

But the problem with using scales as the only method of tracking progress is that most scales only show the total body weight. But it does not show fat and muscle mass, which is an important factor in assessing health, because:

  • Too much body fat (especially visceral fat) are associated with many health problems and can increase the risk of chronic diseases such as diabetes, cancer and heart disease:
  • In contrast, a healthy ratio of muscle mass to body fat can improve your health while reducing your risk of the above diseases.

Your body weight can vary significantly from day to day. And these changes are more related to changes in the amount of water and intestinal contents in your body than to an increase or decrease in the amount of fat. Here are some factors that significantly affect body weight:

  • The ratio of sodium and potassium. These two electrolytes are contained in most of our everyday foods and determine how much water is retained in our cells;
  • Glycogen stores in muscles. One gram of glycogen attracts at least three grams of water. Glycogen reserves are depleted by movement and replenished by eating;
  • Creatine stores. Like glycogen, creatine attracts water so its stores are replenished and depleted;
  • The amount of food in the digestive tract. There will always be more or less food in our body that has not been completely processed and removed from the body. The regularity of toilet visits, stress, the amount of food and drink, the amount of fiber, etc., determine how much food is in our digestive tract at any given moment. Accordingly, it is also a constantly changing quantity, which has a rather significant impact on our weight;
  • Menstrual cycle – in women, during the menstrual cycle, the hormonal balance changes all the time and can significantly affect water retention and, therefore, body weight;
  • Carbohydrate consumption. Carbohydrates also attract water and since we do not take the same amount of carbohydrates every day - our weight also increases when we take more of them and decreases when we have less of them in our body;
  • Another type of water retention. The body is a very complex "mechanism" and there are many reasons why it retains water. For instance - sleep quality;
  • Muscle gain or loss. Although the changes in muscle mass during the day are small, it also affects our weight;
  • Changes in body fat mass. Yes, fat mass also cannot significantly increase or decrease in one day. However, it changes, and that influences our weight.

Why this long enumeration?

To demonstrate clearly that using only body weight, it is almost impossible to understand how the ratio of fat and muscle mass in our body changes.

That the amount of water in our body and the contents of the digestive tract significantly affects our weight.

That jumping on the scales every day is pointless.

That in order to better assess the changes taking place in your body, in addition to your body weight, it is advisable to use other methods to measure your progress.

Then let's talk about them.


How to estimate the amount of fat in your body?

To be able to evaluate and compare your progress with the "standard", let's start with some conventional parameters.

Healthy body fat percentage depending on gender and age.

Age (years)



















Average values (body fat percentage) observed in athletes and people with high, moderate, and low levels of physical activity:

Classification group






People with high physical activity



People with moderate physical activity



People with obesity

32% and above

25% and above

Source: American College of Sports Medicine guidelines


Various methods are used to assess body composition. Some of them are very simple and easy to use, while others are quite complex.

The most accurate methods are usually expensive and used only for research purposes.

However, there are a few simple methods that give you a good idea of whether your body composition is changing and in which direction it is changing:

  • How does your strength change with each workout? Can you lift more, perform exercises more times, perform increasingly difficult/complex exercises;
  • Body weight. Weigh yourself no more than once a week in the morning, after visiting the toilet, on an empty stomach;
  • Mirror, clothes, and photos. Take photos once every 2 to 4 weeks - in the same clothing, location, and time of day (lighting).
  • Circumferences:
    • Leg calves (in the widest part);
    • Thighs (about 5 cm below the groin);
    • Hips (at widest point);
    • Abdomen (for women at the narrowest point, for men at the height of the navel);
    • Chest (under the shoulders);
    • Hands (relaxed, at their widest point);
    • Neck (in the narrowest part).

The circumferences should be measured every 2-4 weeks:

  • Standing straight and with a relaxed body (without cutting out the chest or tucking in the stomach);
  • At the same time of day;
  • Do not take measurements after physical activity, especially strength training, as then your muscles will be bigger;
  • When measuring, the measuring tape should always be stretched evenly – not too tight and not too loose. Otherwise, the measurements will be incorrect, because our bodies are "soft", and different tension of the measuring tape will give you different results, even if there are no real changes.

In women, the menstrual cycle also affects measurements – therefore, to get correct results, try to take measurements on the same day of the cycle.


How to interpret the obtained results?

As the main indicators, we will use changes in body weight, waist circumference, and strength.

Changes in fat and muscle mass

Body weight

Waist circumference


Fat mass decreases. Muscle mass does not change.




Muscle mass increases. Fat mass does not change.




Uniform recomposition of the body - fat mass decreases, and muscle mass increases.




Both fat and muscle mass increase.




Both fat and muscle mass decrease.




Fat mass increases and muscle mass decreases.





Other body composition assessment methods

Skinfold measurements

Skinfold measurements have been used to estimate body fat for over 50 years.

The thickness of the subcutaneous fat is measured. Measurements are taken on 3 or 7 different parts of the body, which differ in men and women:

  • 3-point measurements for women – triceps, area above the hip bone, and thigh or stomach;
  • 7-point measurements for women – the chest, area under the armpit, and area under the shoulder blade are also measured;
  • 3-point measurements for men – chest, abdomen and thigh or chest, triceps, and the area under the shoulder blade;
  • 7-point measurements for men - the areas under the armpit and under the shoulder blade are also measured.

Advantages: The simplest skinfold measuring calipers are inexpensive, and measurements can be made quickly and practically anywhere.

Disadvantages: The method requires practice and basic knowledge of anatomy.

Availability: Calipers at an affordable price are available both in pharmacies and online stores.

Accuracy: Depends on the skill of the person making the measurements. Measurement errors can vary from 3.5% to 5% of body fat.


Dual Energy X-ray Absorptiometry (DXA)

The percentage of body fat is measured. The measurement is performed using X-rays of two different energy levels.

DXA scan lasts about 10 minutes.

The radiation level during DXA scanning is very low - about the same as what you would get in three hours of your normal life.

DXA is also used to assess bone density and provides detailed information about bone, lean mass, and fat in specific areas of the body - arms, legs, and torso.


Advantages: This method provides very accurate and detailed information about both the total amount of fat and its distribution in different parts of the body. And also bone density readings.

Disadvantages: DXA is not freely available to the general public and is also quite an expensive procedure.

Availability: DXA is usually only available in medical and research facilities.

Accuracy: DXA is one of the most accurate measurement methods. The error rate ranges from 2.5% to 3.5% of body fat.


Hydrostatic weighing

This method is also known as underwater weighing or hydrodensitometry, determines your body composition based on its density.

2 measurements are made:

  • As you submerge under water and exhale as much air as possible from your lungs;
  • While on dry land, and the amount of air left in the lungs after exhalation is also estimated or measured.

The data obtained is used to determine the density of your body. Your body density is then used to predict the percentage of body fat.


Advantages: The method is accurate, relatively fast, and simple.

Disadvantages: It can be difficult or even impossible for some people to use because you have to exhale as much air as possible and then hold your breath underwater.

Availability: Hydrostatic weighing is generally only available in medical and research facilities.

Accuracy: If the testing is done correctly, the error may amount to about 2% of body fat.


Air Displacement Plethysmography (Bod Pod)

Similar to hydrostatic weighing, air displacement plethysmography (ADP) calculates your body fat percentage based on your body density.

Only unlike hydrostatic weighing, ADP uses air instead of water to determine body density. The ratio between air volume and pressure allows this device to determine the density of your body.

The measurement is made in an egg-shaped chamber in which the air pressure changes within a few minutes.

To get accurate measurements, it is necessary to wear tight-fitting clothing or a swimming suit during testing.


Advantages: The method is accurate and relatively fast.

Disadvantages: ADP is limited in availability and can be quite expensive.

Availability: ADP is generally only available in medical and research facilities.

Accuracy: The error rate ranges from 2% to 4% body fat.


Bioelectrical Impedance Analysis (BIA)

BIA devices detect, how your body reacts to small electrical discharges.

The measurement is made by sending small pulses of electric current through your body and analyzing how easily they pass through your tissues.

Electric current passes more easily through muscles than through fat, because muscles contain more water.

There are many different BIA devices that vary greatly in cost, complexity, and accuracy, including smart scales designed for home use.


Advantages: BIA is a fast and simple method, and many BIA devices are widely available (for example, smart scales).

Disadvantages: Accuracy varies greatly and can be affected by both food and fluid intake.

Availability: Although BIA devices are widely available, those designed for home use are often less accurate than those used in medical or research facilities.

Accuracy: The accuracy depends on the quality of each particular device. The error rate varies from 3.8% to 5% fat. But it may be higher if cheap and/or low-quality devices are used.


Bioimpedance spectroscopy (BIS)

BIS is similar to BIA in that both methods measure the body's response to small electrical currents. BIS and BIA devices look similar, but use different technologies and also analyze the information obtained during the measurement differently.

The calculations of BIA and BIS are based on equations, and therefore the accuracy of both of these methods depends on how much each particular person is similar to the people on the basis of whose data/reactions these equations were developed.


Advantages: BIS is a quick and easy method.

Disadvantages: Unlike BIA, BIS devices are not currently available for home use.

Availability: BIS is only available in medical and research facilities.

Accuracy: BIS devices are probably a bit more accurate than BIA devices designed for home use. The error rate ranges from 3% to 5% of body fat.


Electrical Impedance Myography (EIM)

Electrical resistance myography is a third method that measures the body's response to small electrical currents.

The method differs in that the measurement is performed locally - body composition is only measured at one specific location.  

This technology is used in devices that are relatively cheap and available to almost everyone.


Advantages: BIS is a quick and easy method.

Disadvantages: There is very little information on the accuracy of these devices.

Availability: The devices are cheap and widely available.

Accuracy: More research is needed to determine the accuracy of this method.


3-D body scanners

Infrared sensors detect the shape of your body and create a three-dimensional model of it.

The scanner then determines your body fat percentage based on your body measurements and shape.

In fact, a three-dimensional body scanner is the same measurements of circumferences – only there are more of them and they are more accurate.


Advantages: 3-D body scanning is relatively quick and easy.

Disadvantages: 3-D body scanners are not currently widely available.

Accuracy: Information is limited, but some 3-D scanners can be quite accurate with an error of about 4%.


Key takeaways

When you step on the scales, you will find out how much you weigh.

But if you want to get a more accurate idea of your body composition, you need to take additional measurements.

The choice is quite wide. The following control questions will help you choose the most suitable option:

  • What is the purpose of measuring your body fat percentage?
  • How important is measurement accuracy?
  • How often would you like to take measurements?
  • Do you want to take measurements at home?
  • How important are measurement costs?

Regardless of which method you choose, it is important to always use the same method, as changing it will lead to changes in the data /measurement results and can lead to many misunderstandings. If you evaluate yourself the same way every time, the error rate will decrease and you will be able to evaluate your progress more accurately/more easily.

The best time to take measurements is in the morning, after visiting the toilet and on an empty stomach.

Remember that the amount of water in your body affects the results of measurements based on electrical signals (BIA, BIS, and EIM). Therefore, if you use these methods, do not drink liquids for at least one hour before taking the measurement.

Even the best methods are not perfect and give only a rough idea of your body fat amount - so when interpreting the results, be more pessimistic than optimistic -😊.

Your body composition is influenced by your eating habits, physical activity, sleep, and other factors, so measuring progress can sometimes seem difficult.

If you choose not a simple weight loss, but a recomposition of the body, the evaluation of the results will become even more difficult, as weight loss will occur more slowly or not at all.


When you simultaneously reduce fat mass and increase muscle mass, your appearance will change, but the weight change can be very small.

Good luck!


In addition, I recommend reading this article - Why does the girth decrease but the weight does not drop?

The Epidemiology of Obesity

Percent body fat is a better predictor of cardiovascular risk factors than body mass index

Body Composition in Type 2 Diabetes: Change in Quality and not Just Quantity that Matters

Obesity, Body Composition, and Breast Cancer

Functional body composition: insights into the regulation of energy metabolism and some clinical applications

Effect of resistance training on resting metabolic rate and its estimation by a dual-energy X-ray absorptiometry metabolic map

Relationship between muscle water and glycogen recovery after prolonged exercise in the heat in humans

Reference values for body composition and anthropometric measurements in athletes

Ultrasonography is not more reliable than anthropometry for assessing visceral fat in obese children

Age-related hormonal adaptations, muscle circumference and strength development with 8 weeks moderate intensity resistance training

Human body composition

Body composition: health and performance in exercise and sport

Body Composition and Physical Health in Sports Practice

Prediction of total adiposity from skinfolds and the curvilinear relationship between external and internal adiposity

ACSM's resource manual for Guidelines for exercise testing and prescription

A new air displacement method for the determination of human body composition

Bioelectrical impedance analysis–part I: review of principles and methods

Analytical assessment of the various bioimpedance methods used to estimate body water

An investigation of the accuracy and reliability of body composition assessed with a handheld electrical impedance myography device

Evaluation of a rotary laser body scanner for body volume and fat assessment

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