Bioimpedance analysis and water in the human body

Curated by Gerolamo Cavalli and Gabriele Gualandris

It does not seem to interest anyone, or at least a few; we are mainly interested in body fat, to the limit of lean mass ... And water? This lack of interest is curious, given that we are made of water for 65% of our weight.

An adult man of about 70Kg should have about 45 liters in his body, it seems strange but it is really so! To realize the importance and the actual value of all this, just think that a newborn is 80% hydrated, while a very old person has a hydration close to 50%. It seems clear that aging is nothing more than a slow dehydration, we talk so much about magic anti-age formulas, but about body water? Furthermore, physiology tells us that the lack of water, both intracellular (ICW), and extracellular (ECW), makes it difficult for any activity in our body to function properly. It will therefore be important to be hydrated in order to be healthy, and to ensure that all physiological / metabolic mechanisms function at their best. it must also be clear that the state of hydration in the body is not directly related to how much water you drink. In fact, even if you drink a lot, you can be dehydrated, because the water balance is regulated by several factors, including osmosis, the concentration of sodium and potassium and others.

A 2% drop in water at the intracellular level seriously compromises an athlete's performance, the 7% decrease can cause serious damage to the body.

But can we measure how much water I have in my body?

Of course, yes, it is enough to simply undergo bioimpedance analysis (BIA)

What is BIA?

It is a medical device (similar to the instrument with which you make the electrocardiogram at rest when you join the gym), and is used, for example, in the field of kidney failure and in high-level sports, but its field of application is practically infinite. Water can be measured at practically everyone, so you can know the hydration status of the person, then intervene on a practical level by changing the training, nutrition, lifestyle, etc. It is a tool that really provides a large number of data, very important for the high-level professional, doctor, dietician or personal trainer.

But is it painful to undergo BIA?

Absolutely not, you just have to lie down for ten minutes, just relax.

How much does it cost to undergo BIA bioipedenziomedria

On average 20/30 euros.

How does the instrument measure water in my body?

Practically electrodes are applied to the hands and feet, and the instrument causes a slight electric current to pass through your body. Quite simply we say that the instrument measures the resistance offered by the body to this current, even if we must say that the impedance is based on a non-trivial technology, derived from the American military aviation in the 70s / 80s to test the pilots, so as to avoid even a slight dehydration that could lead to discomfort with the consequent risk of losing the aircraft.

Does BIA only measure water?

The instrument measures both intracellular and extracellular water, and mathematically extrapolates a large amount of data, including fat mass (FM) and lean mass (FFM), with excellent precision if you are in normoratation. In practice, it divides the body into three compartments: fat, lean and water.

If I am offered to undergo the BIA, how do I know if the equipment with which the examination is carried out is really valid?

It is not easy if you do not have competence in the matter, but a small trick can be used. In general all the applications that are made with the person in an orthostatic position (standing) are not valid instruments that are passed off as bioimpedance instruments and cost a few euros. A serious instrumentation, on the other hand, costs a few thousand euros and the exam is always performed by supine (lying on your back) on a cot.

What are the advantages of BIA compared to other methods for establishing body composition?

The most logical comparison I make, also because it is perhaps the most widespread system, is with plicometry, which, pinching some parts of the body with a specific tweezer, estimates body fat. He does not measure it then, but he estimates it, dividing the body into only two compartments: lean mass (FFM) and fat mass (FM), but of water, in this method, it is not talked about, and it is the one that should interest you before all the rest.

But where can I go to the BIA or who should I contact to do it?

The important thing about BIA is not to do it, but to have someone who knows how to use the results. In general, to do it, you can turn to sports medicine centers, but for a more practical application you can contact your Sports Doctor, Dietician or Personal Trainer.

Should I repeat the bioimpedance periodically?

Obviously yes, to check for any changes in body composition. In the field of training, on average it is repeated in a time that varies from every 2 months to every 6 months, depending on the objectives, the results of the first bioimpedance, the variants that have been introduced and other things.

Lastly: how is it that I've never seen advertising, never heard anyone speak of impedance?

In reality, the fact is that BIA is not known. This depends mainly on two reasons:

• Changes in body composition are also tangible for the client / patient, and this can prove to be a double-edged sword, so many professionals prefer to continue working with methods where the results are less understandable by the client / patient.
• At an advertising and commercial level, it is better to push, for example, a slimming cream, thanks to which you have large revenues, than to advertise something with which you do not earn money easily, which moreover requires commitment and high professionalism, and that in fact, it really only earns the customer.