Why do I get inconsistent results with segmental body composition measurement?

Body impedance measurement can be very sensitive to hydration, skin-to-skin contact, foot cleanliness, and dry skin. For example, drinking a glass of water can significantly shift your metrics. 

It is really important to avoid skin-to-skin contact by making sure your hands and your arms are not touching the skin of your torso, and your thighs are not touching each other. If you find it difficult, an easy workaround is to perform the measurement wearing light clothes. This cloth barrier helps to prevent skin-to-skin contact.

It is also strongly advised to perform measurements :

• At the same time of the day, ideally in the morning
• in the same hydration conditions (doing it shortly after waking up is generally a good idea!), with an empty bladder.
• With clean feet
• And avoid eating or drinking up to 2 hours before taking a measurement. 

Important: Body composition measurements on the Body Scan require the handle. It is also important to avoid skin-to-skin contact by making sure your hands and your arms are not touching the skin of your torso, and your thighs are not touching each other.

Please see our article for the best practices for taking segmental body composition measurements.  

Why is Body Scan giving different results than other Withings scales, or other scales that do not have handles?

Body Scan might give different body composition results than other Withings scales, or other scales that do not have handles, for two main reasons:

1. Body Scan performs a segmental body composition measurement using 8 electrodes: 4 located on the main body (glass plate) and 4 located on the handle. As a result, the current used for the measurement flows from the hands to the feet and thus through the entire body. This measurement is more accurate than a measurement on a scale without a handle where the current only flows through the lower body, i.e. from one leg to another. Body Scan measures an accurate body impedance value due to this innovation. 
   
2. Body Scan measures the values of impedance at 3 different frequencies up to 250kHz, in order to give the most accurate results possible. Impedance measurement at high frequency (> 200kHz) makes it possible to measure the amount of water inside the cells (intracellular) from the amount of water outside of the cells (extracellular), which when added up give the total body water. With standard scales, the total amount of water has to be extrapolated from the measure of the amount of extracellular water. 

Note that even though earlier generation BIA scales are less accurate, the trends they provide for all metrics remains reliable.

Note: Body composition is only available for people 18 years or older. Children and teenagers younger than 18 won't be able to access this feature.