- How it works
- How to ensure accurate results
- What the result means
- 1. Fat mass
- 2. Lean mass
- 3. Muscle mass
- 4. Hydration
- 5. Bone density
- 6. Visceral fat
- 7. Basal metabolism rate
Bioimpedance is an exam that analyzes body composition, indicating the approximate amount of muscle, bone and fat. This exam is widely used in gyms and as a complement to nutrition consultations to evaluate the results of the training plan or diet, for example, and can be carried out every 3 or 6 months to compare results and verify any evolution of body composition.
This type of examination is done on special scales, such as Tanita or Omron, which have metal plates that conduct a weak type of electrical current that runs through the entire body.
Therefore, in addition to the current weight, these scales also show the amount of muscle, fat, water and even the calories that the body burns throughout the day, according to sex, age, height and intensity of physical activity, which are data entered in the balance.
Understand how it works in our fun video:
How it works
Bioimpedance devices are able to assess the percentage of fat, muscle, bones and water in the body because an electric current passes through the body through metal plates. This current travels easily through water and, therefore, highly hydrated tissues, such as muscles, let the current pass quickly. Fat and bones, on the other hand, have little water and, therefore, the current has greater difficulty in passing.
And so the difference between the resistance of fat, in letting the current pass, and the speed with which it passes through tissues such as muscles, for example, allows the device to calculate the value that indicates the amount of lean mass, fat and Water.
Thus, to know the composition of the body, it is enough to climb barefoot, and without socks, in a Tanita, for example, or to hold, in the hands, the metal plates of another type of smaller device. The biggest difference between these two bioimpedance methods is that, on the scale, the results are more accurate for the composition of the lower half of the body, while on the device, which is held in the hands, the result refers to the composition of the trunk, arms and head. In this way, the most accurate way of knowing body composition is to use a scale that combines the two methods.
How to ensure accurate results
For the exam to indicate the correct values of fat and lean mass, it is necessary to guarantee some conditions, such as:
- Avoid eating, drinking coffee or exercising in the previous 4 hours; Drink 2 to 4 glasses of water 2 hours before the exam. Do not drink alcoholic beverages in the previous 24 hours; Do not apply cream on your feet or hands.
In addition, using light and small parts helps to ensure that the results are as accurate as possible.
All preparation is very important because, for example, with regard to water, if there is not adequate hydration, the body has less water for the electric current to flow and, therefore, the fat mass value may be higher than the real.
When there is fluid retention, it is also important to take it as soon as possible, and inform the technician, as the excess water in the body can lead to an increase in the amount of lean mass, which also does not reflect reality.
What the result means
In addition to weight and body mass index (BMI), the different values offered by bioimpedance devices, or scales, are:
1. Fat mass
The amount of fat mass can be given in% or kg, depending on the type of appliance. The recommended values of fat mass vary according to sex and age in percentage, as shown in the table below:
| Age | Men | Women | ||||
| Low | Normal | High | Low | Normal | High | |
| 15 to 24 | <13.1 | 13.2 to 18.6 | > 18.7 | <22.9 | 23 to 29.6 | > 29.7 |
| 25 to 34 | <15.2 | 15.3 to 21.8 | > 21.9 | <22.8 | 22.9 to 29.7 | > 29.8 |
| 35 to 44 | <16.1 | 16.2 to 23.1 | > 23.2 | <22.7 | 22.8 to 29.8 | > 29.9 |
| 45 to 54 | <16.5 | 16.6 to 23.7 | > 23.8 | <23.3 | 23.4 to 31.9 | > 32.0 |
| 55 to 64 | <17.7 | 17.8 to 26.3 | > 26.4 | <28.3 | 28.4 to 35.9 | > 36.0 |
| 65 to 74 | <19.8 | 19.9 to 27.5 | > 27.6 | <31.4 | 31.5 to 39.8 | > 39.9 |
| 75 to 84 | <21.1 | 21.2 to 27.9 | > 28.0 | <32.8 | 32.9 to 40.3 | > 40.4 |
| > 85 | <25.9 | 25.6 to 31.3 | > 31.4 | <31.2 | 31.3 to 42.4 | > 42.5 |
Ideally, the value of fat mass should be in the range referred to as normal, because when it is above this value it means that there is a lot of accumulated fat, which increases the risk of various diseases, such as obesity or diabetes.
Athletes, on the other hand, usually have a lower fat mass value than normal, see in this table which is the ideal fat mass for your height and weight.
2. Lean mass
The lean mass value indicates the amount of muscle and water in the body, and some more modern scales and devices already make the difference between the two values. For lean mass, the recommended values in Kg are:
| Age | Men | Women | ||||
| Low | Normal | High | Low | Normal | High | |
| 15 to 24 | <54.7 | 54.8 to 62.3 | > 62.4 | <39.9 | 40.0 to 44.9 | > 45.0 |
| 24 to 34 | <56.5 | 56.6 to 63.5 | > 63.6 | <39.9 | 40.0 to 45.4 | > 45.5 |
| 35 to 44 | <56.3 | 58.4 to 63.6 | > 63.7 | <40.0 | 40.1 to 45.3 | > 45.4 |
| 45 to 54 | <55.3 | 55.2 to 61.5 | > 61.6 | <40.2 | 40.3 to 45.6 | > 45.7 |
| 55 to 64 | <54.0 | 54.1 to 61.5 | > 61.6 | <38.7 | 38.8 to 44.7 | > 44.8 |
| 65 to 74 | <53.2 | 53.3 to 61.2 | > 61.1 | <38.4 | 38.5 to 45.4 | > 45.5 |
| 75 to 84 | <50.5 | 50.6 to 58.1 | > 58.2 | <36.2 | 36.3 to 42.1 | > 42.2 |
| > 85 | <48.5 | 48.6 to 53.2 | > 53.3 | <33.6 | 33.7 to 39.9 | > 40.0 |
Similar to fat mass, lean mass must also be in the range of values defined as normal, however, athletes generally have higher values due to frequent workouts that facilitate muscle building. Sedentary people or those who do not work out in the gym, usually have a lower value.
Lean mass is usually used to evaluate the results of a training plan, for example, as it allows you to assess whether you are gaining muscle with the type of exercise you are doing.
3. Muscle mass
Normally, muscle mass should increase during bioimpedance assessments, as the greater the amount of muscle, the greater the amount of calories expended per day, which allows you to more easily eliminate excess fat from the body and prevent the appearance of various cardiovascular diseases. This information can be given in pounds of muscle or percentage.
The amount of muscle mass shows only the weight of the muscles within the lean mass, not counting water and other body tissues, for example. This type of mass also includes the smooth muscles of some organs, such as the stomach or intestine, as well as the cardiac muscle.
4. Hydration
The reference values for the amount of water in men and women are different and are described below:
- Women: 45% to 60%; Man: 50% to 65%.
This value is very important to know if the body is well hydrated, which ensures the health of the muscles, prevents cramps, ruptures and injuries, ensuring a progressive improvement in performance and training results.
Thus, when the value is below the reference range, it is advisable to increase the water intake per day, to about 2 liters, in order to avoid becoming dehydrated.
5. Bone density
The bone density value, or bone weight, must be constant over time to ensure that the bones are healthy and to follow the evolution of bone density, which is why it is very important to evaluate the benefits of physical activity in the elderly or people with osteopenia or osteoporosis, for example, since the regular practice of physical exercise allows to strengthen the bones and, many times, to treat the loss of bone density.
Also find out which are the best exercises to strengthen bones and improve bone density in the next bioimpedance exam.
6. Visceral fat
Visceral fat is the amount of fat that is stored in the abdominal region, around vital organs, such as the heart. The value can vary between 1 and 59, being divided into two groups:
- Healthy: 1 to 12; Harmful: 13 to 59.
Although the presence of visceral fat helps to protect the organs, excess fat is harmful and can cause various diseases, such as high blood pressure, diabetes and even heart failure.
7. Basal metabolism rate
Basal metabolism is the amount of calories that the body uses to function, and that number is calculated based on the age, sex and physical activity that is introduced in the scale.
Knowing this value is very useful for people who are on a diet to know how much they have to eat less to lose weight or how many more calories must be taken to put on weight.
In addition, the devices can also display the metabolic age that represents the age for which the current metabolism rate is recommended. Thus, the metabolic age must always be equal to or less than the current age for it to be a positive result for a healthy person.
In order to increase the metabolism rate, the amount of lean mass must be increased and this consequently reduces fat mass, as muscle is an active tissue and uses more calories than fat, contributing to the increase in the burning of calories from the diet. or stored body fat.
These scales over time get cheaper and cheaper although the price of a bioimpedance scale is still higher than a conventional scale, it is a very interesting way to keep your shape under surveillance, and the benefits can outweigh the money spent.
