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Principles of Estimating Body Fat Percentage
The Tanita Body Fat Monitor/Scale BF-572 allows you to
estimate your weight and body fat percentage at home as
easily as you measure your weight. This model also
includes Tanita's Graph feature, so you can track your
results over time.
What is Body Fat Percentage?
Body fat percentage is the percentage of fat in your body. Until
now, your absolute weight has determined whether or not you
were considered overweight or obese. In recent years,the defini-
tion of obesity has been refined to mean the presence of excess
body fat. Too much body fat has been linked to conditions such
as high blood pressure, heart disease, diabetes, cancer, and other
disabling conditions.
The chart below shows four ranges of body fat percentage.
Body Fat Ranges for Standard Adults
Underfat
Female
20–39
Age
40–59
60–79
0%
10%
Male
20–39
Age
40–59
60–79
Underfat
1.
Based on NIH/WHO BMI Guidelines.
2.
As reported by Gallagher, et al., at NY Obesity Research Center.
To determine the percentage of body fat that is appropriate for your body, consult your physician.
The BIA Method
The BF-572 uses the BIA (Bioelectrical Impedance
Analysis) method. In this method, a safe low-level
electrical signal is passed through the body. It is dif-
ficult 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 amount of fat in the body
can be accurately estimated by measuring the
impedance. The signal used is very low-level,
making it safe and imperceptible.
2
1 ., 2.
Healthy
Overfat
Obese
20%
30%
40%
Healthy
Overfat
Obese
Body Fat Percentage Fluctuations in a Day
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 con-
sistent time of day under consistent conditions.
Besides this basic cycle of fluctuations in the daily body fat readings,
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.
The graph below shows an example of daily body fat percentage
fluctuations, based on the BIA method.
Body Fat %
22
21
20
19
18
17
6 am
10 am
2 pm
Advantages of Tanita's BIA Method
Previously, body fat percentage was determined by measuring the
thickness of subcutaneous fat by pinching it with calipers, or by
laying a person on a scanning bed and passing a current from hand
to foot. However, these methods present problems—professional
skills are required, the procedures take time and are often invasive,
and measurement values vary. Currently, the gold standard methods
of fat percentage measurement are DEXA (dual energy x-ray absorp-
tiometry) and Hydrodensitometry (underwater weighing).
Tanita's BIA method uses equations derived from large, multi-ethnic
population studies to predict body composition. Readings taken
with Tanita's BF-572 correlate highly with both DEXA (Tanita's ref-
erence model) and Hydrodensitometry.
6 pm
10 pm
Time
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