iHealth Core body scale analysis uses state of the art technology, BIA (Bioelectrical Impedance Analysis). This method of body fat analysis is very accurate and easy to use. However, changes in hydration levels can affect readings. If your body is dehydrated, you will likely experience a higher than normal reading. If you are over-hydrated, you could experience a slightly lower reading. To obtain the greatest accuracy and repeatability from our product, we suggest the following protocol.
- Take readings at least 3 hours after rising, eating a large meal, or exercising.
- Take readings once a week at the same time of day under the same conditions. (Note: Taking readings more than once per week is not beneficial since body fat does not change from day to day.)
- Average your readings for the month.
- Compare averages from month to month.
By following this format, hydration fluctuations throughout the month will average out, and you will be able to better assess any real change in your body fat percentage over time.
*credit to Sylvain of iHealth Labs EU
https://helpcenter.ihealthlabs.eu/hc/en-gb/articles/208801545-iHealth-Core-HS6-Why-does-my-body-fat-percent-fluctuate-