The TANITA body fat monitor/weighing scale uses BIA (Bioelectrical Impedance Analysis) technology. This method of body fat analysis has high repeatability and is easy to use; however, normal daily changes in hydration levels affect the measurements. When your hydration level is lower, you are likely to see a higher fat percentage. When your hydration level is higher, you are likely to see a lower fat percentage.

To minimise the effect of the normal daily body water and/or weight fluctuations on the measurements, it's advised to take measurements at the same time of day and under the same circumstances as much as possible.

• 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.)
• Do not perform a measurement after exercising. Exercise affects our bodies in a number of ways and leaves us in an "inconsistent" state, this can lead to inconsistent results. Always measure before exercising, or keep at least 8 hours between exercising and measuring.
• The electrodes need skin contact, do not measure with socks or tights on, this will lead to inaccurate results or no results at all and an ‘Error’ message.
• Average your readings for the month.
• Compare averages from month to month.

For more information about which factors influence your measurements. Please check out:

Why do my measurements fluctuate?