COMPARISON OF BODY COMPOSITION ANALYSIS AND FAT FREE MASS ...

[Pages:6]Journal of Hygienic Engineering and Design

Original scientific paper UDC 613.25:572.512.087.1-055.2-057.875(437.6)

COMPARISON OF BODY COMPOSITION ANALYSIS AND FAT FREE MASS USING AIR DISPLACEMENT PLETHYSMOGRAPHY VERSUS BIOELECTRICAL

IMPEDANCE ANALYSIS

Marianna Schwarzov?1*, Katar?na Fatrcov?-Sramkov?1, Nat?lia Sabov?1, Miroslava Kac?niov?2, Eva Tvrd?3

1Department of Human Nutrition, Faculty of Agrobiology and Food Resources, Slovak University of Agriculture in Nitra, Tr. A. Hlinku 2, 94901 Nitra, Slovak Republic

2Department of Fruit Science, Viticulture and Enology, Faculty of Horticulture and Landscape Engineering, Slovak University of Agriculture in Nitra, Tr. A. Hlinku 2, 94901 Nitra, Slovak Republic 3Department of Animal Physiology, Faculty of Biotechnology and Food Sciences, Slovak University of Agriculture in Nitra, Tr. A. Hlinku 2, 94901 Nitra, Slovak Republic

*e-mail: marianna.schwarzova@uniag.sk

Abstract

Obesity is one of the leading causes of premature mortality and morbidity worldwide. Diagnosing and evaluating body composition is very important.The aim was to compare different methods of body composition analysis: air displacement plethysmography (ADP) versus multifrequency bioelectrical impedance analysis (MF-BIA) in a young healthy women.

Body composition analysis was performed in a group of young healthy women (n = 33) aged 21 to 27 years from the Slovak University of Agriculture in Nitra. The body density was estimated by ADP using the device BOD POD (Cosmed Inc., Concord, CA, USA). Data for the estimation of the body fat by plethysmographic method have been reported to agree closely with the traditional gold standard hydrodensitometry underwater weighing. ADP is accepted as a suitable alternative. The percentage of body fat was estimated from the body density using the Siri equation. ADP using BOD POD versus BIA were compared based on the determination of fat free mass (% FFM): ADP versus BIA using Bodystat QuadScan 4000 (Isle of Man, UK), ADP versus BIA using InBodyS10 (Biospace, Korea), ADP versus BIA using InBody720 (Biospace, Korea). For statistical evaluation we used ANOVA, nonparametric correlation analysis (Spearman's coefficient) and statistical software Statistica Cz 10 (Dell Statistica, USA).

The BIA method using the Bodystat QuadScan 4000 provided higher FFM values by an average of 6.25 ? 4.64% (p < 0.001) versus ADP. The values from the

InBody S10 were higher by 1.48 ? 3.83% (p < 0.05) and by the InBody 720 method by 1.4 ? 3.94% (p < 0.05) versus ADP. We found a moderate correlation of FFM (%) obtained from the BIA methods with values from the ADP method (r = 0.642 to 0.78). BIA devices gave statistically significantly higher results than the ADP method (p < 0.001). When comparing the results of the % FFM in young adult healthy women, the correlation of FFM from the BIA method and the application of three different devices with the values from ADP was strong. The highest correlation coefficient was when evaluating the dependence of the BIA method using InBody S10 and ADP devices. FFM was significantly higher with the BIA method for all types of devices, but most markedly with the Bodystat QuadScan 4000 compared to ADP.

The body composition methods used BIA and ADP are very effective in assessing body composition, but are not interchangeable, providing different estimates in a sample of healthy young women.

Key words: Body composition, Fat free mass, Air displacement plethysmography, Bioelectrical impedance analysis, Women.

1. Introduction

Obesity is one of the leading causes of premature mortality and morbidity worldwide [1]. In 2016, 39% of adults aged 18 years and over (39% of men and

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40% of women) were overweight. Overall, about 13% of the world's adult population (11% of men and 15% of women) were obese in 2016. The worldwide prevalence of obesity nearly tripled between 1975 and 2016. As of 2016, 20.5% of Slovaks older than 18 years old were reported to be obese [2]. The adult obesity rate in Slovakia is among the lowest in the EU. One in seven adults was obese in 2017, which is below the EU average, and the rate has remained roughly stable over the past 15 years. However, overweight and obesity are growing issues in children. One in six 15-year-olds was overweight or obese in 2013 - 2014, a rate that has nearly doubled since 2001 - 2002 [3]. These numbers have been steadily and continually increasing over the last years with a growing trend.

Body composition is an important indicator of health and nutritional status. Due to the rise of overweight and obesity, it is very important to diagnose and evaluate the body composition. Considerably (imperative) it is to have valid and reliable body composition assessment tools to accurately classify normal, overweight and obese individuals, in order to suggest suitable treatment options such as appropriate nutrition and exercise interventions, and to detect and/or to monitor body composition changes in time.

There are numerous methods applicable to the evaluation of body composition. Underwater weighting, air displacement plethysmography and particularly dual-energy x-ray absorptiometry (DEXA) are among the most common reference methods [4].

Air displacement plethysmography (ADP) is technique that uses measurements of body density for the estimation of body composition [5]. This technique calculates the body volume by measuring the volume of displaced air by a subject inside the capsule of a machine [6]. ADP has several advantages over DEXA, which is considered to be the gold standard method. ADP is less expensive and does not expose subjects to radiation when compared to DEXA. In addition, ADP can measure subjects of various sizes [7], requires less technician training [8] and was found to be reliable in various populations [9, 10].

Bioelectrical impedance analysis (BIA) has emerged as a popular method of assessing the body composition as it is a quick, portable, and a relatively inexpensive technique. The traditional supine (arm-to-leg) BIA method has been shown to be accurate in assessing the percentage fat mass (%FM) of groups but not of individuals [11, 12]. During measurement using the newer leg-to-leg BIA, a weak current is passed up the leg, across the pelvis, and down the other leg. Small metal foot plates measure the voltage drop that is generated as the current passes through the subjects' body. BIA theory proposes that this voltage drop is caused by the relative composition of the subjects body; fat provides

a greater resistance to the current than fat-free mass (lean soft tissue, water, etc.), allowing an effective quantification of each body compartment [13]. BIA analysers are very portable and simple to use, making them ideal for field studies or preliminary screening, potentially offering a more discriminatory measure than body mass index (BMI) [14]. It is well recognized that the BIA technique, if properly validated, could become a more practical option for epidemiological and another types of studies.

However, little research has been conducted to assess BIA validity and reliability in normal, overweight and obese Slovak women. Therefore, the purpose of this study was to evaluate the validity of BIA in comparison to the ADP criterion for body composition measurement in young female university students. Furthermore, we aimed to determine, compare and evaluate specific differences between the values of the body composition measured by a variety of BIA analysers that vary in the applied electric current frequency, number of electrodes and flow of the electric current through individual body parts.

2. Materials and Methods

2.1 Subjects

Thirty-three young Caucasian healthy women aged 21 to 27 years volunteered to participate in this study. Descriptive statistics are shown in Table 1.

Table 1. Summary of the general characteristics of the volunteers (n = 33)

Parameters

Mean ? SD

Range

Age (years)

23.47 ? 1.08 21.29 - 26.58

Height (cm)

167.06 ? 5.91 156.00 - 180.00

Weight (kg)

62.44 ? 8.24 51.55 - 83.73

Body fat (%) Visceral fat area (cm2) Body mass index (kg/m2)

28.65 ? 6.00 68.18 ? 17.79 22.62 ? 2.50

19.00 - 39.70 36.10 - 110.30 18.90 - 28.80

The study was conducted in accordance with the Declaration of Helsinki, and the protocol was approved by the Specialized St. Svorad Hospital Nitra Zobor Ethic Committee (Protocol number: 3/120620/2020). All subjects read, understood and provided written informed consent prior to study participation. The females were university students studying human nutrition, we can apply their results on the general population of women without any medical problems.

2.2 Procedures

The volunteers reported to the Laboratory of Department of Human Nutrition SUA in Nitra to

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undergo the ADP and BIA testing following an eighthour fasting period. The participants were informed of the instructions they had to follow prior to the measurement (no alcohol consumption for 24 hours, no vigorous exercise in less than 12 hours, no food and beverages 3 hours prior to the measurement, urination immediately before measurement; only women that did not have their period were measured). The participants attended all measurements wearing underwear. The measurement was executed in a standing (BIA) or sitting position in a capsule (ADP, BOD POD), and was always performed the same team of experienced researchers. To exclude any potential impact on the collected data due to delays between measurements (e.g. by consumption of liquids or food), all assessments were executed in immediate succession. The body height, which served as an input parameter for all analyzers used in the study, was measured using the A-213 anthropometer (Trystom, Olomouc, Czech Republic). The body weight as an input parameter for the Bodystat QuadScan and InBodyS10 analyzer, was taken by the BOD POD.

2.3 Air displacement plethysmography

Air displacement plethysmography (ADP, BOD POD, Cosmed Inc., Concord, CA, USA) was used to estimate body volume using the device's default software (Software Version 4.2+, Cosmed Inc., Concord, CA, USA). Prior to each test, the BOD POD was calibrated according to the manufacturer's instructions. The subjects weight and body volume were measured and used to determine fat mas (FM; kg), fat free mass (FFM; kg) and percent body fat (%BF; %). Equations established by Brozek et al., [15], and Siri, [16], were used to estimate the body composition.

2.4 Bioelectrical impedance analysis

The fat free mass (FFM; kg), fat mass (FM; kg), and total body water (TBW; L) of each participant was successively measured on all applied BIA analyzers in the following order: Bodystat QuadScan 4000 (Isle of Man, UK), InBodyS10 (Biospace, Korea), and InBody720 (Biospace, Korea). The used analysers for the body composition diagnostics differed in the applied electric current frequency, number of electrodes and flow of the electric current through the individual body parts. Basic characteristics of the analysers are provided as follows:

- Bodystat QuadScan 4000 (Isle of Man, UK) (arm-toleg) is a multi-frequency BIA analyser that uses the electric current frequency of 5, 50, 100 and 200 kHz for the measurement. Four-point touch electrodes are used for the assessment.

- InBodyS10 (Biospace, Seoul, Korea) (leg-to-leg) is a tetrapolar multi-frequency BIA analyser that uses the gradual electric current frequency of 1, 5, 50, 250, 500 and 1000 kHz for the measurement. Eight-point touch type electrodes are used for the assessment. The placement of electrodes is different in comparison to InBody720. The analyser is not a digital scale.

- InBody720 (Biospace, Seoul, Korea) (leg-to-leg) is a tetrapolar multi-frequency BIA analyser that uses the gradual electric current frequency of 1, 5, 50, 250, 500 and 1000 kHz for the measurement. Eight-point touch type electrodes are used for the assessment. The analyser is also a digital scale.

2.5 Statistical analysis

The normality of distribution was verified by the Shapiro-Wilk test.With regard to the normal distribution of values, a paired t-test was used to test for statistical significance of the differences in FFM between the BIA and ADP methods. In addition, Pearson's productmoment correlation was used to determine the relationship between the two methods. The Bland and Altman, [17], method was used to calculate the limits of agreement between BIA and ADP for the assessment of FFM. The statistical significance level was determined to be = 0.05 for all tests used. With respect to the values where statistically significant differences were found, Cohen's d coefficient was calculated to determine the magnitude of the change. Subsequently, this was interpreted using the following criteria: 0.2 = small; 0.5 ? 0.8 = moderate; and > 0.8 = large effect size. Statistica Cz Version 10 (Dell Statistica, USA) was used to perform the paired t-test and correlation analysis.

3. Results and Discussion

Validity statistics for %FFM between BIA devices and ADP are presented in Table 2.

Table 2. Validity statistics for the FFM between bioelectrical impedance analyse (BIA) and air displacement plethysmography (ADP)

Parameters

Fat free mass

(FFM; %)

CV (%) r

(mean ? SD)

ADP

71.35 ? 6.00

8.41

BIA Bodystat QuadScan 4000

77.60 ? 4.48

5.78 0.643*

BIA InBody S10

72.84 ? 5.46

7.50 0.780*

BIA InBody 720

72.75 ? 5.43

7.46 0.767*

*Significant at p 0.05; CV (%) - Coefficient of variation; r - Pearson's correlation coefficient.

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The paired t-test revealed a significant difference for %FFM measured by BIA device Bodystat QuadScan 4000 when compared to ADP (mean difference ? SD; 6.25 ? 4.64 %; p < 0.001; d = 1.180). There was a significant difference between the BIA device InBody S10 and ADP in %FFM ( 1.49 ? 3.83 %; p < 0.05; d = 0.258). A significant difference was observed in case of %FFM between BIA device InBody720 and ADP measurements ( 1.40 ? 3.94 %; p < 0.05; d = 0.244). Pearsons correlation coefficient demonstrated a significant correlation for %FFM between all three BIA analyzers and ADP (Table 2).

The BIA method using the Bodystat QuadScan 4000 provided higher FFM values by an average of 6.25 ? 4.64% (p < 0.001) versus ADP and a large effect size was found (d = 1.180). The values from the InBody S10 were higher by 1.48 ? 3.83% (p < 0.05) and by the InBody 720 method by 1.40 ? 3.94% (p < 0.05) versus ADP, but only small practical significance was recorded (d = 0.258; respectively 0.244 for InBody 720). We found a moderate correlation of %FFM obtained from the BIA methods with values from the ADP

method (r = 0.64 to 0.78) (Table 2). BIA devices gave significantly higher results than the ADP method (p < 0.001). When comparing the results of the %FFM in young adult healthy women, the correlation of FFM from the BIA method and the application of three different devices with the values from ADP was moderate. The highest correlation coefficient was when evaluating the dependence of the BIA method using InBody S10 and ADP devices. The values of Pearsons correlation coefficient r explain 42 - 61% of variability. Bland-Altman analyses were performed for %FFM to determine if bias existed between BIA devices and ADP, with plots shown in Figure 1.

A significant trend was observed for %FFM, indicating bias between the three BIA devices and ADP methods. FFM was significantly higher with the BIA method for all types of devices, but most markedly with the Bodystat QuadScan 4000 when compared to ADP.

The study used BIA devices that take advantage of different frequencies for the measurement, with electric current going through different body parts,

Figure 1. The Bland-Altman plots with 95% limits of agreement and correlation analysis of the differences between % of Fat free mass (%FFM) measured by the BIA and ADP

a) The middle solid line represents the mean difference between %FFM from the Bioelectrical impedance analyse (BIA) analyzer Bodystat QuadScan 4000 - %FFM from air displacement plethysmography (ADP) and the upper and lower dashed lines represent ? 2 SD from the mean. Bias between BIA and ADP was observed for %FFM, as indicated by a significant p value (p < 0.001); b) The middle solid line represents the mean difference between %FFM from the Bioelectrical impedance analyse (BIA) analyzer InBody S10 - %FFM from air displacement plethysmography (ADP) and the upper and lower dashed lines represent ? 2 SD from the mean. Bias between BIA and ADP was observed for %FFM, as indicated by a significant p value (p < 0.05); c) The middle solid line represents the mean difference between %FFM from the Bioelectrical impedance analyse (BIA) analyzer InBody 720 - %FFM from air displacement plethysmography (ADP) and the upper and lower dashed lines represent ? 2 SD from the mean. Bias between BIA and ADP was not observed for %FFM, as indicated by a significant p value (p < 0.05)

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and that dispose of different number and types of electrodes. The aim of this study was to evaluate their validity against the reference method - air displacement plethysmography. The BIA method [18, 19, 20, and 14] and ADP have been extensively validated against DEXA [21, 14]. For the InBody analysers, the correlation with DEXA reference method was determined to be at the level of 0.94 - 0.96 in the case of healthy men and women aged 18 years [22]. Von Hurst et al., [14], report that BIA demonstrated an excellent relative agreement with ADP and DEXA. Nevertheless, it must be noted that the complete agreement was biased and the interface was reported to be wide. BIA underestimated body fat by 2%. This underestimation was observed at all %FM values and there were no differences between men and women. In our study, we observed a similar trend of FM underestimation and FFM overestimation by BIA in comparison to ADP, but the differences observed were higher. It must be however said that due to the size of the sample, they were expected.

BIA was found to be a valid method for %FFM when compared to ADP. However, all BIA devices significantly overestimated FFM when compared with ADP. Also, in other studies, higher average values of fat free mass were measured by the BIA method when compared to the ADP method. Findings published by Houska et al., [23], suggest that similar to female track-and-field athletes who also exhibited lean muscular physiques, %BF was overestimated by BIA and ADP in female cheerleaders as opposed to underwater weighing (UWW).

The assessment of FFM is of considerable importance in the evaluation of the nutritional status in epidemiological, clinical and scientific studies. It is one of the prime diagnostic criteria for the diagnosis of cachexia and it is significantly associated with morbidity and mortality. An important fact is the common observation of low FFM values in the normal overweight and sarcopenia population, which are independently associated with adverse health and disability outcomes. These are the reasons why there is a need for methods to measure the body composition in different environments. Reference methods (DEXA, UWW) are expensive, with a limited availability, and require experienced personnel. As such, the applicability of these methods in routine clinical and research conditions is limited. Alternative methods such as BIA are non-invasive, relatively simple and safe methods for the determination of fat and fat free mass in normally hydrated individuals [24, 25, and 26].

3.1 Study limitation

We are aware of the fact that the obtained results might be affected by the selected groups. The limitations of this study lie in the examination of an exclusively

female population; followed by the lack of agreement with statistical analysis reported in the literature; and the fact that the interpretation of the results does not provide conclusions that can be extrapolated to other populations. The validity of the results is also limited by the used BIA analysers. Since there is a wide range of BIA devices, the present study could serve as a base for a potential inclusion of other BIA analysers, or different population groups in the research.

Even though the differences between the mean values measured by the used devices were low in majority of the cases and ranged at the level of the errors of measurement, a detailed analysis showed substantially higher differences in several subjects.

Acknowledgement

This research has been supported by European Fund for Regional Development (projects ITMS 26220220115 and ITMS 26220220180), and by projects APVV 15/0229, KEGA-024SPU-4/2018, KEGA 012UKF-4/2019.

4. Conclusions

- Our results show significant differences between BIA analysers and the ADP method for the estimation of the body composition. Although the differences between the mean values measured by the selected equipment were in most cases low and ranged at the level of measurement errors, it must be stated that they were significant.

- A detailed analysis showed significantly higher differences in several subjects. It is therefore probable and obvious that a high correlation of the measured values does not guarantee the concordance of the results. The BIA and ADP methods are very effective in assessing the body composition, but are not interchangeable, providing different estimates in a sample of healthy young women.

- Replacing the analyser with another could lead to incorrect interpretation of the measured values in diagnosing and estimating the body composition. Further studies should be carried out to improve estimates against reference standards in all sections of the population.

5. References

[1] Murtagh E., and NCD Risk Factor Collaboration. (2017). Worldwide trends in body-mass index, underweight, overweight, and obesity from 1975 to 2016: A pooled analysis of 2416 population-based measurement studies in 128.9 million children, adolescents, and adults. The Lancet, 390, (10113), pp. 2627-2642.

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[2] WHO. (2016). Obesity and overweight. World Health Organization. ................
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