Body Fat Percentage is measured through
different methods. Some methods of estimating body fat
are expensive, require special laboratory equipment,
and are not readily available.
1. Skin-Fold Callipers/Body Fat Calipers
Body fat can be measured using simple skin-fold
calipers. It is used to measure the amount of fat just
under the skin at areas like: upper-arm, upper-back,
lower-back, stomach and upper thigh. These fat-measurements
are then averaged and put into a formula to determine
the total body fat percentage. It relies on as assumption
that the thickness of the fat below the skin is proportional
to the fat stored deeper in the body.
2. Bioelectrical Impedance (BI)
Bioelectrical impedance involves sending a
small electrical signal through the body. The more muscle
a person has, the more water their body is able to hold.
The greater amount of water in a person's body, the
easier it is for the current to pass through, the more
fat present in a person's body, more resistance is blocking
the signal. Bioelectrical impedance can be quite accurate
but the results are affected by intake of food, body
temperature and water intake.
3. DEXA (Dual Energy X-ray Absorptiometry)
The DEXA machine measures bone density. However,
it can also measure body fat percentage. It uses a body
scanner and two low-dose x-rays to read bone mass and
soft tissue mass. From start to finish, it takes about
10-20 minutes to do a body scan. It offers a high degree
of precision in measuring body fat percentage but the
process is expensive.
4.Underwater Weighing
The percent body
fat is calculated on the basis of the density of
the body. The density of the body is calculated by an
equation that involves measuring a person suspended
on a trapeze in the air and then weighing the person
under water.
5. Body Mass Index
Body Mass Index (BMI) is a relationship between
weight and height that is associated with body
fat and health
risk.
Weight is converted to kilograms; height is converted
to meters and then squared. These numbers are then put
into an equation to determine BMI:
BMI = kg/m2.
6. Girth Measurement
Girth measurements are circumference measurements
taken at a specific body site and recorded. They are
converted to a constant and then entered into a formula
to predict percent body fat. The sites measured differ
depending on a person's age and gender.For ages 18 to
26: Men measure the right biceps, right forearm, and
abdomen. Women measure the abdomen, right thigh and
right forearm. For ages 27 to 50: Men measure the hips
(buttocks), abdomen, and right forearm Women measure
the abdomen, right thigh, and right calf.
7. Near Infrared Interactance
This method uses the principles of light absorption
and reflection to measure body fat. The equipment used
is a computerized spectrophotometer with a single, rapid
scanning monochromator and fiber optic probe. The probe
sends out electromagnetic radiation from the monochromator
to the surface of the biceps of a person's dominant
arm. The signal penetrates the underlying tissue to
a depth of one centimeter. Shifts in the wavelength
of the reflected beam and a prediction equation are
used to compute the percent body fat. |
