what method is use to determine body composition?

Method to determined the body composition

Following are some conventional and advanced method used for BCA .Conventional method comprise of anthropometer (BMI, skinfold thickness, waist to hip ratio), while advance methods include bioelectrical impedance analysis (BIA), densitometry, dual energy X-ray absorptiometry (DEXA), computed tomography (CT scan) and isotope dilution method.

Selecting an appropriate method is crucial and plays a pivotal role in body composition analysis . Following are some of the points to be considered while selecting an appropriate BCA method.

Coast to be incurred for the technique;

Purpose for which the body composition is being determined
Time consumed to perform the procedure and convenience
Number of trained personals required for the procedure
Physiological status (age and health) of the subject
Precision and accuracy of the method to be used

Anthropometric methods:

Anthropometric measure are a series of quotative measurements of the bone, muscle and adipose tissue to ascertain, size and composition of the human body. The core element of anthropometer are weight, height, BMI, body circumference (hip, waist, and limbs)and skinfold thickness .

These measures are valuable since they present diagnostics of obesity, which is linearly correlated with the risk of CVDs, hypertension, diabetes mellitus, and other additionally, anthropometric measurement may be used as a baseline indicator for physical fitness.

Body mass index(BMI);

BMI is quickest and the easiest way to predict body FM . Although it is most used technique in nutrition science but has several limitations as it does not give the clear picture of FM and FFM. For example, athlete having more muscular mass would have a BMI higher than normal value , but he has normal body composition and should be considered healthy.

This limitation seek our attention to consider other methods of body composition analysis. BMI lower or higher than normal range(18.5 - 24.9) is strongly correlated with the risk of mortality in both males and females. BMI is measured using standard protocol.

SKINFOLD THICKNESS:

It is another of measuring subcutaneous fat with the help of caliper. It gives an estimation of percentage FM, FFM and body density. It provides more accurate picture about percent body fat as compared to BMI. Particular, skin fold thickness can be used for nutritional assessment of patients where weight can, t be measured.

Total skinfold thickness ( summing up the value of skinfold measurement from multiple sites and then using the equation to calculate the total body fat) also tells about obesity .It is cheap, quick, simple and non- invasive technique to measure body composition.

However , there are limitations associated with skinfold thickness as more than 100 predictive equation are available varying from region to region and for different population groups, compromising the accuracy of this method. For achieving high levels of precision and accuracy, trained staff is required.

Skinfold thickness can be measured from single site and multiple sites. Single-site skinfold thickness itself does not give estimates about the total FM of the body. However, it can be used to calculate arm fat area which is correlated with total body fat . The method works on the premise that fat is equally distributed within the body and thickness of skinfold is a measure of subcutaneous fat.

Moreover, it can be used to estimate the risk of muscle wasting particularly in conjunction with arm circumference measurement. Furthermore, individual measurements can be compared with sex and age specific reference data to identify one, s nutritional status.

Single site skinfold thickness is measured by pinching the triceps muscle with calipers to see triceps skinfold. Mid upper arm circumference is measured using standard protocol.

Total body mass can be estimated by:

Arm fat area= Triceps skinfold multiple MUAC/ 2-3.14multiple(tricep skinfold )2/4

Arm muscle area is calculated by the following equation.

Arm muscle area=MUAC - (3.14 multiply tricep skinfold)2/4 3.14

Estimate for body fat:

For the estimation of the body fat, we need body density, which is derived from multiple skinfold thickness. Body density is estimated by using Durbin- Womersley equations which are age and gender specific. These equations are based on the sum of skinfold thickness from bicep, triceps, subscapular and sacroiliac.

Age Equation

Females

17-19 B.D=1.1620-0.0630*log(sum of skinfold)

20-29 B.D=1.1631-0.0632* log (sum of skinfold)

30-39 B.D=1.1422-0.0544*log(sum of skinfold)

40-49 B.D=1.1620-0.0700*log(sum of skinfold)

50+ B.D=1.1715-0.0779*log(sum of skinfold)

Male

17-19 B.D=1.1549-0.0678*log(sum of skinfold)

20-29 B.D=1.1599-0.0717*log(sum of skinfold)

30-39 B.D=1.1423-0.0632*log(sum of skinfold)

40-49 B.D=1.1333-0.0612*log(sum of skinfold)

50+ B.D=1.1339-0.0645*log(sum of skinfold)

By known body density 9B.D) we can estimate fat mass by the following equation:

Siri equation: %body fat=9495/BD)-450

Table NO: Cut - of value for % body fat

Health classification body fat(%)

Females Males

Unhealthy (very low) <8 <5

Acceptable(lower side) 9-23 6-15

Acceptable(upper side) 14-31 16-24

Unhealthy(very high) >32 >25

Waist circumference and waist to hip ratio;

Waist circumference and waist to hip ratio are the measure of eternal obesity (accumulation of fatty mass in the abdominal area) . these measure are strongly correlated with BMI, percent body fat, subcutaneous and intra - abdominal fat in both men and women . It is measured using standard .

Waist circumference is more accurate predicator of CVDs, diabetes and early death than BMI . However these methods have limitations as it is difficult to take accurate measurement especially around hip.

They are not recommended for children and does not give the accurate values in person shorter than 5 feet. Moreover, they are not suitable measurement tools for individuals having BMI higher than 35.

Anthropometric Indicator Women Men

measure