Tanita UM-041 - Manual (Page 5)

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What is Total Body Water Percentage?
Total Body Water Percentage is the total amount of fluid in a person’s body expressed as a percentage of their total weight.
Approximately 50 –65% of the weight of a healthy person is water. Water plays a vital role in many of the body’s processes and is
found in every cell, tissue and organ. Maintaining a healthy total body water percentage will ensure the body functions efficiently and
will reduce the risk of developing associated health problems.
How To Measure Total Body Water?
Deuterium Dilution Method is currently used as a typical method to measure a total body water percentage. This instrument estimates
the total body percentage by the analysis (Multiple Regression Analysis) based on the parameter found by the BIA method.
A mutuality over 0.8 is obtained between this instrument and the “deuterium dilution method”.
Note:
Deuterium Dilution Method is in terms of total body water based on the analysis of the dilution of orally ingested deuterium
oxide in urine.
Healthy Total Body Water Percentage (%TBW)
The average total body water percentage ranges for a healthy adult are:
Female: 45 to 60%
Male: 50 to 65%
Note:
The total body water percentage of a person with a high percentage of body fat may fall below the average healthy ranges.
Daily Rhythm of Total Body Water
Try to measure total body water percentage at the same time of day and under the same conditions. This increases the accuracy of
the readings. The best time is in the early evening, before the evening meal, when hydration levels are more stable. Total body water
percentage tends to be underestimated to a degree if measured immediately after getting out of bed, not only because of dehydration
but also because the fluid in the body will be stored centrally in the body’s trunk.
As the day progresses this fluid becomes more evenly distributed due to the effect of gravity.
On the contrary, it may be overestimated after exercise or taking a bath because of the movement of body water or a rise in
the body temperature despite actual dehydration.
Important Notes
• Take your measurements at the same time of day and under the same conditions.
• Measured results depend on the movement of water in the body and/or changes in body temperature. Factors affecting total body
water levels include sleep, physical activity, eating and drinking, illness and medications, bathing patterns and urination.
• Take fluid immediately if you have any symptoms of dehydration, particularly after physical activity or bathing.
Symptoms include a dry mouth, headache, nausea, dizziness, skin dryness, a rise in temperature, loss of concentration, etc. If
symptoms persist, consult your doctor immediately.
• Elderly people are at increased risk of dehydration as they have less sensitivity to thirst and other rational symptoms.
• This instrument cannot be used to specifically determine an individual’s recommended total body water percentage.
Look for the long-term changes in total body water percentage and try to maintain a consistent, healthy total body water percentage.
Normal
(Female)
Normal
(Male)
TBW by BIA [%] TBW by BIA [%]
TBW by D20 dilution
method [%]
TBW by D20 dilution
method [%]