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PRINCIPLES OF ESTIMATING BODY FAT PERCENTAGE
Tanita Body Fat Monitor/Scales allow you to determine your body fat
percentage at home as easily as you measure your weight.
What is Body Fat Percentage?
Body fat percentage is the percentage of fat in your body. Too much body
fat has been linked to conditions such as high blood pressure, heart
disease, diabetes, cancer, and other disabling conditions.
The BIA Method
Tanita Body Fat Monitor/Scales use the BIA (Bioelectrical Impedance
Analysis) technique. In this method, a safe, low-level electrical signal is
passed through the body. It is difficult for the signal to flow through fat in
the human body, but easy to flow through moisture in the muscle and other
body tissues. The difficulty with which a signal flows through a substance
is called impedance. So the more resistance, or impedance, the signal
encounters, the higher the body fat reading.
Hydration FIuctuations
Hydration levels in the body may affect body fat readings. Readings are
usually highest in the early waking hours, since the body tends to be
dehydrated after a long night’s sleep. For the most accurate reading, a
person should take a body fat percentage reading at a consistent time of day
under consistent conditions.
Besides this basic cycle of fluctuations in the daily body fat readings using
BIA, variations may be caused by hydration changes in the body due to
eating, drinking, menstruation, illness, exercising, and bathing. Daily body
fat readings are unique to each person, and depend upon one’s lifestyle, job
and activities.
Tanita’s patented “foot-pad”
design sends a safe, low-
level electrical signal
through the body to
determine its composition.
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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
The Deuterium Dilution Method is currently used as a typical method to measure total body water (TBW) percentage. In
contrast, this instrument estimates TBW by using BIA. An agreement of over 80% is obtained between this instrument
and the Deuterium Dilution Method.
Note: The Deuterium Dilution Method measures total body water based on the analysis of the deuterium oxide isotope in urine before and after
ingestion of an oral dose.
Normal Total Body Water Percentage (% TBW)
The normal total body water percentage ranges for adults are:
Female: 45-60%
Male : 50-65%
Note: The total body water percentage of a person with a high percentage of body fat may fall below the normal ranges.
Daily Rhythm of Total Body Water
Try to monitor 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. Total body water percentage
is not affected by fluids consumed until they are absorbed by the body tissues.
Important Notes
• Take your measurements at the same time of day and under the same conditions.
•Measured results depend on the redistribution 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 fluids 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 symptoms.
• This instrument does not directly measure an individual's total body water content. The percentage reading from the
monitor is only an estimate. Look for long-term changes and try to maintain a consistent, healthy total body water
percentage.
• This instrument will not give total body water readings for children.
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