In recent years, they have been added to the range of mechanical and electronic personal scales. In addition to weight, these scales measure the proportion of muscle mass (rich in water) and fat massor even for the most sophisticated, visceral fat, the most dangerous for health because it coats organs such as the heart or the liver.
How it works ?
Impedancemetry is the measurement of the resistance of the human body to the diffusion of an electric current. The technique was first developed in the 1980s by a Japanese company (Tanita), for hospital nutrition services. But little by little, the devices have taken over the offices of nutritionists, physiotherapists, certain pharmacies and sports halls and finally our bathrooms.
The principle. The scale plate, as well as its handles when there are any (for the most sophisticated models), are equipped with electrodes that send an electric current of very low intensity (we don’t feel anything!) through the feet, even the hands. The current quickly passes through the muscular areas, rich in water, but encounters its greatest resistance when it reaches the fatty areas: it is this resistance, called impedance, which is measured. From the data collected, the device calculates body composition: fat and water in percentage, muscle and bone in kilograms. It also indicates the expected values according to sex and age, which makes it possible to check whether we are “in the nails” or not.
Water/grease: what relationship?
Over the years, body composition changes: the proportion of water and muscle mass decrease, fat mass increases.
How to use it well?
The basic rules. Manufacturers recommend weighing yourself on an empty stomach, but during the day, for example before dinner, rather than in the morning when you get out of bed, at a time when we are inevitably a little dehydrated. When you go on a diet or exercise, you must space out each weighing by at least 15 days to be able to see the changes. Make sure your feet and hands are dry and free from wounds and position them correctly on the electrodes.
Precautions. “In certain situations, the measurements are wrongisays Dr Boris Hansel, endocrinologist-nutritionist (Bichat hospital, Paris). The proportion of water is abnormally low after sports training during which you sweat, or if you take medication diuretic (for example, in case of hypertension). Conversely, it is higher than normal if you suffer from edema caused by heart or kidney disease. In addition, wearing a metal prosthesis modifies the flow of the pulsed current.”
A contraindication. “Wearing a pacemaker (pacemaker), whose operation may be altered by current, is contraindicated“, adds the specialist. Generally speaking, it is better to seek the advice of your doctor before investing.
Are these scales really useful?
YES, when you are concerned about your figure. These scales allow to judge the benefit of losing weight, because calculating the body mass index (BMI*) is not enough. You can very well have a normal weight, with a BMI between 18.5 and 25 (values defined by the World Health Organization), but an excessive proportion of fat mass, predisposing to type 2 diabetes and cardio diseases. -vascular. Conversely, you can have a borderline BMI, between 25 and 27, but a high proportion of muscles, a predictive factor of good health.
YES, routinely. These devices can help track changes in our body composition long term, over several months or years. Because what matters is it is the evolution of the results on the same scaleeven though the measurements are less reliable than those of professional equipment.
BMI = weight in kilos / height in meters, squared. For example, for a weight of 60 k and a height of 1.62 m, BMI = 60 / 1.62 x 1.62 = 22.9.
3 tips before buying an impedance meter scale 1 – The device must delivera multi-frequency current
which allows a more detailed analysis. 2 – We opt fora scale equipped with handles
which measures body composition in each part of the body (trunk, legs, arms) if you think you have lost a lot of muscle as a result of multiple diets or a serious illness. 3 – We favor a scale measuring visceral fat
if we mainly have kilos located around the stomach.
The measured data is useful to the treating physician
Do these scales really help improve your lifestyle?
For the moment, no study shows that they make it possible to permanently change one’s eating habits or one’s level of physical activity. In my practice, I have the impression that their “motivational effect” only lasts a few weeks. On the other hand, the measured data can be useful to the attending physician to judge the need for a dietary or physical activity prescription.
Are connected scales better? Companion apps help patients track where they stand with graphs showing how their body composition has changed over several months. Some apps also offer workout programs (to increase muscle mass) or dietary advice
which do not, however, replace the advice of a sports coach or a nutrition professional: beware of injuries…
Thanks to Dr. Boris Hansel is the founder of the PuMS (For Better Health) youtube channel.
our selection
BC 545-N from Tanita: the most precise
€228.10 in store or on tanita.fr© Tanita
Withings Body Comp: the most complete In addition to body composition, it indicates the level of visceral fat, pulse wave speed and heart rate, useful data in cardiovascular prevention. Connected, it synchronizes with several health applications.
€199.95 in store or on withings.com© Withings
Master coach Ultra from Terraillon: good value for money
€79.99, in small appliance stores.© Terraillon
Read also :
⋙ Impedancemetry: procedure, diagnosis, contraindications
⋙ How do I know if I am overweight?
⋙ Calculate your ideal weight using impedancemetry
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