Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.593817
Title: The assessment of body composition in obese subjects using bioimpedance spectroscopy
Author: Wijk, M. C. W. van
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1999
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Abstract:
The efficacy of a weight-reducing programme depends on the extent and composition of the weight loss, and the associated changes in body function. The aim of the thesis was to assess the value of BioImpedance Spectroscopy (BIS) to predict changes in total body water (TBW) and whole body and regional body composition in obese subjects (BMI 30-45kg/m2) using deuterium dilution and a four-compartment model as the reference methods. First, equations were created for the prediction of TBW from impedance (SEE: 1.99 kg (males), 1.37 kg (females)). The acceptable level of mean agreement for the prediction of TBW was set at 1.5 kg. Bias SD for males was found to be - 0.283 2.680 kg and bias for females was found to be 0.128 1.705 kg before weight loss. After weight loss bias SD for males was found to be - 0.004 1.963 kg and for females the bias was 0.003 1.349 kg. Therefore the acceptable level of agreement was met for both males and females. Second, fat free mass (FFM) was predicted using the hydration fraction (HF) of fat free mass obtained by the four- compartment model. This HF was found to be 0.756 0.028, with approximately half of the variability due to methodology and the other half to physiology. BIS satisfactorily predicted whole body composition before (bias SD; males -0.942 1.973 kg and females 0.077 2.660 kg) and after weight loss (males -0.238 2.934 kg and females -0.342 1.755 kg) when compared to the four-compartment model (the acceptable level of agreement was set at 2 kg). Approximately 80% of the mean weight loss was due to fat mass and 20% to FFM. Bias ( SD) for change in FFM was -0.687 1.893 kg for males and 0.714 1.904 kg for females. Bias ( SD) for the change in %BF was 0.674 2.116 for males and -0.843 1.843 for females. Therefore, the acceptable level of the mean agreement in change in FFM between BIS and the four-compartment model (set at 0.5 kg FFM) was not met in this study. In other words in this subjects studied in this project BIS did not satisfactorily predict the change in FFM compared to the four-compartment model. Third, BIS satisfactorily predicted regional body composition as validated by magnetic resonance imaging (MRI) before (arm SEE 0.33 kg and leg SEE 0.93 kg) and after weight loss (arm SEE 0.27 kg and leg SEE 0.86 kg). The acceptable level of mean agreement for the assessment of fat mass in the arm and leg were set as 0.25 kg and 0.75 kg respectively. Before weight loss bias SD for males in the arm was found to be 0.02 0.26 kg and for females bias was found to be - 0.02 0.41 kg. After weight loss bias for the arm was found to be 0.02 0.20 kg for males and - 0.00 0.25 kg for females. The bias for the prediction of fat mass in the leg was found to be 0.03 0.26 kg for males and - 0.19 1.02 kg for females before weight loss. After weight loss the bias SD for males was 0.00 0.77 kg and bias for females was 0.00 .42 kg. Therefore the acceptable levels of agreement were met for both males and females. Furthermore, a novel impedance method (site-specific impedance) predicted MRI skinfold thickness (sum of four skinfolds) better than the traditional calipers (r=0.84 v r=-0.21; P0.05). It is concluded that BIS is of value in assessing TBW, whole body and regional composition and skinfold thickness and that the composition of weight loss was predominantly fat.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.593817  DOI: Not available
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