Tanita SC-240 Manuel D'utilisation page 29

Inter-day changes
The diagrams below offer examples of actual
measurements made of inter-day changes. A study was
done to determine the degree of change in the impedance
between the feet during dehydration; the first two days
represent a normal daily routine, while in the latter two
days a state of dehydration was induced using a sauna.
No significant inter-day change was measured in
body weight, impedance between the feet, or body fat
percentage during the normal daily routine. During the
dehydrated state, however, a drop in body weight of 1kg
was noted, with the impedance between the feet rising
approximately 15Ω on the first day of dehydration and
30-35Ω on the second day. As a result, body fat percentage
was up by around 1% on the first day of dehydration and
by 1.5-2% on the second day.
As mentioned earlier, impedance increases when
body weight is reduced (such as by dehydration), and
decreases when body weight is increased through excess
consumption of food and drink. The inter-day change in
impedance is thus inversely proportional to the change in
body weight.
These inter-day changes stem from such causes as:
1) Temporary increases in body weight (total body water) through overeating and overdrinking
2) Dehydration due to heavy sweating during vigorous exercise
3) Dehydration due to alcohol consumption or the use of diuretics
4) Dehydration due to heavy sweating during saunas, etc.
Accordingly, it is recommended that instructions be provided to the subject to help eliminate these
causes when accurate measurements are needed.
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