Assignment Title Metabolic Practical Report
Word Count 1663
Date Submitted 17th April 2018
Extension applied for Yes / No Revised Date
Anthropometry measurements and bio-impedance analysis are accurate predictors of body fat mass percentage.
Bio-impedance scales, skin fold tests, body mass index (BMI), and waist circumference are accurate predictors of fat mass.
To measure and compare (i) % fat from bio-impedance scales, (ii) % fat from skinfold tests, (iii) BMI, and (iv) waist circumference with % fat from the ‘gold standard’ BodPod.
The measurement of body composition is a central topic of many researches because it can provide vital information on wide-ranging populations including individuals that have disease, seemingly healthy, the overweight (obese) as well as athletic individuals. This assessment is really useful to assess information in particular fat mass percentage which allows us to monitor our health and being assisted by appropriate therapeutic interventions as well as maintaining health capacity1. It also helps monitoring development process and progress of metabolic-related diseases such as type 2 diabetes mellitus (T2DM), obesity and cardiovascular diseases (CVD) 2. There are many methods that have been established to estimate % fat mass and each of them require specific equipment and trained physician. Bio-impedance analysis (BIA) is fairly simple and a non-invasive method with less variability to assess body composition which based on determining the electrical resistance through the body 3, 4. Anthropometry such as skinfold thickness (SKF), waist circumference (WC) and body mass index (BMI) are also being used in measuring body composition 5. They also found to be good predictors for % fat mass 6. Skinfold thickness measurement also quite simple and easy method. In addition, there is the most currently developed technology based on system for air-displacement plethysmography, which is known by the trade name COSMED BodPod. This COSMED BodPod has been classified as ‘gold standard’ since it gives reliable and highly accurate result in determining body composition especially body fat and body density 7, 8 . Now, the problem is all those traditional techniques that being used to assess % fat mass has been questioned its reliability and their accuracy in predicting the % fat mass compared to ‘gold standard’ BodPod as the reference method. Furthermore, body composition assessments may differ in its accuracy and in the target tissue of interest 9. Therefore, the purpose of this study was trying to compare all those different techniques for their accuracy and reliability by using % fat mass values obtained from BodPod as the reference.
A total of 180 students from BIOM3020 (Integrated Endocrinology) course, age (19-30) were recruited to participate in this study. Written informed consent was obtained by each of the subjects before the study was conducted. The whole study and protocols were approved by the BellberryHuman Research Ethics Committee (HREC) who reviewed this study in accordance with the National Health and Medical Research Council’s (NHMRC) National Statement on Ethical Conduct in Human Research.
Percentage fat mass obtained from BodPod was used as the reference values in this study. Subjects has been requested to change into their tight fitting clothing and empty their bladder before undergo BodPod. This is to minimize potential error due to air trapped in clothing and excess water volume. Briefly, subjects while wearing tight fitting clothing and a swim cap, sitting within the BodPod chamber and followed the instructions by the experienced tutor on what to do.
Confidential Page 3 4/16/2018
Waist circumference in centimetres, skinfold thickness in millimetres and collecting data from bio-impedance analysis (BIA) were performed by a trained tutor to reduce variability. For height measurement, subjects were requested to remove their shoes before height measurement were taken by using wall mounted roll-up height measurer. BIA measurements were taken using a bio-impedance scale. Four measurement sites have been used including triceps, biceps, subscapular and suprailiac for skinfold thickness measurements by gently pinched using the calipers. The sum of the four skinfold values was then calculated based on a table developed by Durnin and Womersley (1974) to obtain the estimate of fat mass percentage. Waist circumference was measured using a measuring tape midway between the lowest rib and the top of hipbone which is roughly in line with belly button. Body mass index (BMI) for each subjects were calculated as weight/height², (kg/m²). Weight values obtained from BodPod results were used in this calculation instead of values from bio-impedance scales since BodPod provide more accurate results as a ‘gold standard’.
Data were analysed using GraphPad Prism 7.00. The normal distribution of the data was tested using the D’Agostino & Pearson normality test. Correlation test and linear regression analysis was performed to assess the accuracy and correlation of each selected predictive parameters to estimate % fat mass compared to BodPod. Then, Bland-Altman Plots were used to check the agreement between each parameter. P-value
Assignment Title Metabolic Practical Report