BMI. Here are three letters that you know well and which obviously designate the Body Mass Index. Namely a quickly calculated data which allows you to know if the ratio between your weight and your height is good… or not. Only what your BMI does not say is what the weight in question is made up of.
“You can be very heavy and have a very high BMI because of water retention or a large muscle mass. fat mass which has a negative impact on the functioning of the body, explains Stéphanie Dufant.
THE” IMG (or Fat Mass Index), therefore makes it possible to assess this amount of fat in the body, and “to determine if a person is overweight. It allows you to detach yourself from the weight and to go beyond this data which can contain a lot of different things.”
How do you measure the IMG?
The IMG is measured in two different ways: thanks to impedancemetry or thanks to DEXA. What is the first? This is a low-intensity electrical current that is passed through your body to analyze its tissues. “This involves scales or more or less sophisticated body composition measuring devices”, explains the dietician.
And the DEXA ? This is based on a principle “two-photon x-ray absorption. It is a machine similar to those used to measure bone densitometry.” Suffice to say something that you won’t find at the local supermarket: “These are machines that cost several thousand – even tens of thousands – of euros. Not everyone has this in their office, while you will find medical impedancemetry devices more easily at dieticians or nutritionists. . “
Even at your place? “Yes, but commercial scales are not very reliable because they only have two inputs, through the feet. Medical measuring devices have four inputs and go through the ankles. and the wrists, which allows electricity to pass throughout the body and to have a very precise measurement. “ However, the former are not totally unnecessary: “What we can follow, for example, is the evolution of the data from one time to another. Especially if we are trying to lose weight for health reasons. Even if the figure is not not calculated very precisely, this allows you to know if you are on the right track or not. “
Towards the end of BMI?
The IMG being more precise and reliable than the IMC, should we still trust the second clue? “We are gradually moving away from it, but it remains a standard. In particular because the scientific community has not yet fully validated the use of impedancemetry. It is a small calculation which has limits, but which is so practical that it remains a reference! “
One thing is certain, however, the IMG is gaining ground: “I have been working for 15 years, and the measurement of the fat mass index has really been democratized for 5 or 6 years. We now have efficient and accessible devices. They are also found in hospital services more widely. . “ Let the BMI therefore take it for granted …
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