various method of body composition

1. Presentation on : Measurement of
body composition

2. Assessing Body Composition
The different types of methods used in the
determination of body composition may be
discussed under the following
•Chemical analysis of whole body
•Physical measurement or nutritional
anthropometry
•Advance methods
The search for valid methods of measuring
body composition that are practical and
inexpensive is an ongoing process for
exercise scientists and nutritionists.

3. •Total body potassium using 40k:
Potassium in intracellular fluid index for fat free mass in
healthy subjects assuming that free mass has a constant
amount of k. A constant fraction (0.02gama)of k in body as
isotope 40k- units gama rays or 1.46mev. allowing
(measures radiation) by spectrometer.
•The measurement of k in body
•Calculation of total body k(gms) from 40k
•Conversion of total body k to mmol k
Mmol k= total body k (gms)/atomic count of k (39.098)
•Calculation of fat free mass (kg) from TB k assuming
average fat free mass = 69.4mmol/kg
•Calculation of TB F (kg)= body weight. (kg) – ffm (kg)
•Calculation of % body fat =TBf/body weight * 100

4. Body composition from conductivity
Another method is bioelectrical impedance
analysis (BIA), which uses the resistance of
electrical flow through the body to estimate
body fat. Unfortunately, BIA is highly
sensitive to hydration status and water
intake. Drinking water dilutes the electrolytes
in the body making it less conductive as
does increasing body fat.

5. It is based on change in electrical conductivity
when subject is placed in an electromagnetic field.
Fat free mass is composed of electrolyte-
containing H2O & fat is a poor conductor.
1.Subject lies supine in a long coil to 5MHz current
is passed for few seconds inducing a magnetic .
2. measurement is taken when it is empty. And the
difference re present the measurement

6. Isotope dilution (hygrometry)
Deuterium dilution can be used to measure total body water
TBW, allowing estimation of FFM. A dose of water labelled
with deuterium is given and, following equilibration,
enrichment of the body water pool measured using samples
of either saliva, urine, or blood. Samples are generally
analysed by isotope ratio mass spectrometry; however,
clinical services could be based on a substantially cheaper
but more labour intensive spectrophotometric technique.

7. Other body fluid compartments using isotope
dilution
Estimate the volume of various body fluid compartments, to in turn can
be used to derive estimates of the two components of fat free mass (ffm)
, extracellular mass(ECM) and body cellular mass(BCM).
A dilution technique involving the intravenon injection of 22Na & titrated
H2O- to measure ECM and BF.
BCM is derived from total exchangeable potassium to in turn determine
Ke(kg)=TBW(kg)* R- Na e (kg)
R= sum of Na & K content of sample of whole blood , divided by its
water content (R is a dimensionless constant less than quantity) and
Na e = exchangeable sodium (kg)
Ke is not directly determined from 42k because of short life span of this
isotop.
BCM is estimated by Moore et al (1963)
BCM (kg)= 8.33* Ke
Na e measures fluid not mass
There fore, ECM(kg)= FFM(kg)- BCM(kg)
There fore, body fat = body weight – FFM (kg)

8. Total body nitrogen
Measures body protein mass of nitrogen
bears a fixed ratio to mass of protein (1g N=
6.25g protein)
patients are laid down in sup rive portion
then bomb are lid the patient with cyclotron
or neutron generator. Units X-rays at 10.83Mq
n- are counted by Na I sodium Iodide
detectors from the whole body.
the detected gama –rays counts are
proportional to the absolute mass of total
body N2.

9. Dual energy x ray absorptiometry
Dual energy x ray absorptiometry (DEXA) was developed to
measure bone mineral mass, which is calculated from the
differential absorption of x rays of two different energies. The
body is scanned by 2-x ray beams of high densities &
undisclosed computer programs can be used to estimate bone
minerals, soft tissues , mineral content and density of pelvic
region. It have difficulty in estimating visceral fat and soft
tissues of head.
DXA is quick and acceptable for children down to about 4
years, and can also be used in small infants.

10. Physical measurement or
nutritional anthropometry
Skinfold Method
Skin fold technicians can be trained rather easily, but must
practice on at least 50-100 clients before the skin fold
technique is mastered
The skinfold method of measuring body fat is a practical,
economical, and administratively feasible field technique for
body composition analysis. It involves measuring the skinfold
(subcutaneous fat) thickness at specific sites of the body.
Most equations use the sum of at least three skinfolds to
estimate body density from which body fat may be calculated.

11. This is done using a tool called a calliper
•Take measurements on the
right side of the body.
•Mark client up.
•Pinch skin (KM) above mark
•Pull fat away from muscles
•Place caliper halfway between
top and bottom of mark
•Allow caliper to settle (1–2
seconds)
•Take reading — repeat 15
seconds
•Add up total (4) — average
Calculate body fat %

12. Body composition from body density
The most accurate estimation of body composition is derived from body
density by means of the equation of fractional densities which states that
the overall density of a mixture containing more than one substance (each
with a different density) can be calculated if the proportion and density of
each component substance is known. For determination of body
composition the body is often assumed to be composed of 4 basic
substances ("four compartment model") with the general form of the
equation as follows.
1/Db = w/Dw + f/Df + p/Dp + m/Dm
Where: Db = overall body density, w = proportion of water, f = proportion
of fat, p = proportion of protein, m = proportion of mineral, Dw = density
of water, Df = density of fat, Dp = density of protein, Dm = density of
mineral.

13. In a research laboratory setting
the overall density of the body
(Db) is calculated from its
mass and volume (Db =
mass/volume). The mass of
the body is found by simply
weighing a person on a scale.
The volume of the body is
most easily and accurately
determined by completely
immersing a person in water
and calculating the volume of
water from the weight of water
that is displaced (via
"underwater weighing").

14. Body composition measurement with Whole-Body Air
Displacement Plethysmography (ADP) technology
Another technique for measuring body composition has been
developed for measuring body volume using a different
method than underwater weighing. The technique uses air,
as opposed to water and is known as Whole-Body Air
Displacement Plethysmography (ADP). Subjects enter a
sealed chamber that measures their body volume through the
displacement of air in the chamber. Body volume is combined
with body weight (mass) in order to determine body density.
The technique then estimates the percentage of body fat
and lean body mass (LBM) through empirically derived
equations similar to those used with underwater weighing (for
the density of fat and fat free mass).

15. Magnetic resonance imaging
MRI is an imaging technique that estimates the volume rather than the
mass of adipose tissue. By analysing the absorption and emission of
energy in the radio frequency range of the electromagnetic spectrum, the
technique produces images based on spatial variations in the phase and
frequency of the energy absorbed and emitted. It primarily addresses
hydrogen nuclei, located either in water or fat, and uses these data to
discern tissue types in “imaging slices” which can then be summed to
calculate regional tissue volumes.
Advance methods

16. The main advantage of MRI over other techniques
is its capacity for estimation of regional body
composition, and it is currently the only accurate
and viable approach for the estimation of
intra‐abdominal adipose tissue. However, recent
studies support the use of waist circumference as a
robust index of abdominal fat, and a useful index of
visceral fat.

17. Body composition from total body imaging
Computerized tomography (CT) scan based on the
relationship between the degree of attention of an X-
ray beam & density of the tissues through the beam
has passed.
Patients are laid in supine position in scanner gantry ,
then X- ray beam is passed undergo alteration, the
intensity of patient is recorded and stored in the
scanner computer. It is used to asses change in
visceral organs mass in underweight and obesity. And
not used for pregnant women and children.

18. Body composition from ultrasound
Ultrasound has also been used to
measure subcutaneous fat thickness,
and by using multiple points an
estimation of body composition can
be made.
A high frequency sound waves are
emitted from ultra sound meter which
penetrate the skin and pass through
the adipose tissue and they reach
muscle tissue. At adipose tissue it
interfaces some waves and are
reflected back to meter and noted.
Ultrasound has the advantage of
being able to also directly measure
muscle thickness and quantify
intramuscular fat .

19. Bioelectrical Impedance Analysis
Total body water constitutes the largest component (72%) of
fat-free body weight. Bioelectrical impedance analysis (BIA)
is based on the fact that the body contains intracellular and
extracellular fluids capable of electrical conduction.

20. It measures the impedance of a weak
electric current passed between right
ankle to right wrist of the hand.
Impedance is proportional to square of
the length of the conductor/ subject
divide by its volume. Two electrodes are
placed on wrist and ankle and a thin layer
of gel is applied to skin. The lowest
resistance value is calculated and used
to calculate conductivity and hence it
predicts fat free mass.

21. Chemical method
• Total body
potassium
using 40k
• Body
composition
from
conductivity
• Isotope dilution
(hygrometry)
• Total body
nitrogen
• Dual energy
x ray
absorptiometry
Physical method
• Skinfold Method
• Body
composition from
body density
• Body
composition
measurement
with Whole-Body
Air Displacement
Plethysmography
(ADP) technology
Advance method
• Magnetic
resonance
imaging
• Body
composition
from total body
imaging
• Body
composition
from
ultrasound
• Bioelectrical
Impedance
Analysis

22. Name of
methods
Total body
potassium
using 40k
Body
composition
from
conductivity
Isotope
dilution
(hygrometry)
Total body
nitrogen
Dual energy
x ray
absorptiometr
y
How to measure By usinfg 40k
isotope
By electrical
flow
Deuterium
dilution
1g of nitrogen =
6.25g of protien
body is
scanned by 2-x
ray beams of
high densities
From what to
measure
By measuring
total
potassium in
body
Electrolytes
composition
Fluid of body Na 1 sodium
iodide
absorption
of x rays of two
different
energies
What is
determined
Total body fat Fat free mass Fat free mass Totle body N2 bone mineral
mass

23. Name of
methods
Skinfold
Method
Body composition from body density Body composition
measurement
with Whole-Body Air
Displacement
Plethysmography (ADP
) technology
How to measure Use of caliper 1/Db = w/Dw +
f/Df + p/Dp +
m/Dm
Db = mass/volume In air chamber
From what to
measure
Folding skin Density
of=water,protien,fa
t,minral
Water displacement Air displacement
What is determined body fat Density of body Density of body Body density

24. Name of
methods
Magnetic
resonance
imaging
Body
composition
from total body
imaging
Body
composition
from ultrasound
Bioelectrical
Impedance
Analysis
How to measure By analysing the
absorption and
emission of
energy in the
radio frequency
range of the
electromagnetic
spectrum
X- ray beam high frequency
sound waves
weak electric
current passed
between right
ankle to right
wrist of the hand
From what to
measure
MRI machine C.T. Scan machine Ultrasound
machine
Bioelectrical
impedance
analysis
What is
determined
regional body
composition
It is used to asses
change in visceral
organs mass in
underweight and
obesity
fat thickness fat free mass

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