Body composition: BOD POD method


Body composition is an essential determinant of health status. Athletes need to monitor various parameters of their body composition to keep them within the normal range(Wells and Fewtrell, 2006). Moreover, every other person needs to keep a watch at their body weight and fat composition to avoid growing obese.Currently, the prevalence of obesity is increasing both in children and adults highlighting the importance of body composition monitoring(Reilly et al., 2003). To enhance body composition monitoring, various methods have been developed and approved for use in measurement of body composition. To this end, commercial equipment which employs different principles have been developed and are now used in hospitals and other health facilities. For instance, theBOD POD method has been adopted for use in hospitals to determine body density accurately and the data translated into different body composition parameters. The BOD POD has high precision and accuracy and has been used to detect small changes in both body fat and lean body mass. The results of the BOD POD can be applied to determine the success of nutrition or physical exercise intended to reduce the risk of obesity and lifestyle associated diseases including stroke and diabetes. This scientific poster seeks to find out whether BMI affects fat mass and free fat mass. The research question will be; answered by performing a comparison between methods; BOD POD and Tanita.

Research Question

Does BMI affect fat mass and fat-free mass?


  1. To determine the accuracy of BOD POD in the determination of total body compositions
  2. To assess the accuracy of Tanita body composition monitor
  3. To compare the effects of BMI on fat mass and fat-free mass using BOD POD and Tanita methods

Methods Applied

Two approaches will be used in the study including BOD POD and Tanita. The technique applies different principles hence the results obtained vary.

BOD POD method

There are increasingly many techniques and equipment that can be used to predict body composition including the fat mass and fat-free mass(Wells and Fewtrell, 2006). However, the issue about these techniques which has remained elusive is whether the results from these techniques can be comparable. Thus it is unlikely that a single technique can be applied to all patients in all circumstances. This study seeks to compare the performance of both BOD POD and Tanita in determining the effect of BMI on fat mass and fat-free mass to find an answer to this research question. The BOD POD method applies the air displacement principle to determine body density which is in turn used to assess body composition (fat vs lean). The technique measures body mass/weight using a precise scale and volume. The subject seats in a BOD POD and body density is calculated. Upon calculation of the overall thickness, the proportions of body fat mass and fat-free mass can be determined (Pawar, 2016).

Tanita method

The Tanita body fat analyzer is a relatively new technique applying modern technology to predict the total body fats; both fat mass and fat-free mass. The device utilizes the principle of bioelectrical impedance. The subject stand on the surface plate of the invention and impedance is determined in the legs and the lower body segment(Jebb et al., 2000).

In the current study, a total of 126 students were tested for body composition including both the fat mass and fat-free mass. Various methods were used in the experiment and the results recorded in an excel sheet. Apart from the two main methods, BOD POD, skinfold and segmental analysis methods were also used in the experiment as a reference point/standard for the comparison of BOD POD.



Table 1: Results obtained when BOD POD was used to determine the fat mass, fat-free mass, and the total body mass


Fat mass Fat-free mass Body mass
14.61 47.25 61.24


Upon determining the different parameters which were monitored in this study using the BOD POD method, results were compiled in excel worksheet and later analyzed in SPSS. Mean comparison of the data from the two methods were compared using t-test at p-value =0.05. The results were tabulated in two tables for ease of visual comparison.

Table 2: Results obtained when Tanita was used to determine the fat mass, fat-free mass, and the total body mass

TANITA (Mean Mass)
Fat mass Fat-free mass Body mass
16.27 46.46 61.7


Figure 1 represents the mean comparison of both BOD POD and the Tanita method.There was a slight variation in the two ways. For instance, BOD POD produced a mean fat mass of 14.61kg compared to 16. 27 provided by Tanita. The difference in the mean fat mass was small suggesting that errors could have caused the difference in the mean fat mass during the experiment. On the other hand, BOD POD produces a mean fat-free mass of 47.25kg which is 0.79kg more than that obtained by Tanita. Finally, the total body mass was 61.7 for Tanita and 61.24 for BOD POD. These values were found to be almost the same differencing with a negligible weight of 0.17kg.


Figure 1: Comparison of the mean fat mass, fat-free mass and the body mass at p=0.05 showed that both approaches gave which did not differ with a large margin.



The results for fat mass, fat-free mass and body weight taken using both BO POD and Tanita indicated that the two methods produce almost similar results with only small variations in the percentage fat mass. Fat mass represents the total weight of fats an individual has accumulated in the body. BOD POD an average fat mass of 14.61kg which translates to 23.9% of the total body weight. The percentage of fat mass is slightly higher than the calculated percentage fat mass of 22.4%. The small discrepancy between the two figures can be explained partly by an error that may occur during the process of testing. Besides, equipment calibration and maintenance can cause slight variations in the percentage of fat-free mass (Cole et al., 2000). In a study conducted by Cole and colleagues, there was a slight variation in the percentage of fat-free mass which was associated with different equipment calibration and errors during the process of testing.However, the results obtained by the two methods are in agreement with those obtained by Cole (2000) (Cole et al., 2000). Another important indicator of health is fat-free mass. The fat-free mass is the lean weight, muscles and organ weight without the weight of fats. For a healthy individual, fat-free mass should be an average of 85% of the total body mass(Balagopal et al., 2005).Comparison of the fat-free mass measures obtained by both BOD POD and Tanita showed that BOD POD is relatively more accurate at the estimation of the fat-free mass as compared to Tanita. BOD POD produces an average of 47.24kg with the corresponding total body mass of 61.24kg. This reading translated to 77.2% of the total body mass. A figure which is slightly below the normal average of 85% for a healthy individual. On the other hand, Tanita produced a reading of 75.3% which somewhat lower than that provided by BOD POD. In respect to the free fat mass, BOD is more accurate as compared to Tanita.

Another critical measurement is the total body mass which represents the total body weight including both the fat mass and the fat-free mass. Comparison of the two techniques showed that Tanita produced a reading slightly lower than that provided by the BOD POD. 61.24kg versus 61.7kg

Body Mass Index (BMI) is another important indicator of health.Usually, BMI is arrived at by dividing the total body mass in kg by the individual’s height in square meters. The BMI provides insight into the likelihood of developing obesity. However, some studies suggest that BIM is not an accurate indicator of obesity. These are because there is no clear cut line between normal BMI and high or low BMI somewhat it majorly depends on height which significantly vary between individuals(Shah and Braverman, 2012).

From the results obtained in this study, BMI significantly affects both the fat mass and the fat-free mass because BMI, fat mass and fat-free mass are all affected by the total body mass which as a common factor in the three health indicators. Thus the higher the BMI, the higher the fat mass and fat-free mass.In a study where BMI was compared to free fat mass and fat mass at a t-test p-value of 0.5 and 0.001, it was established that both the fat mass and lose fat mass change as the BMI changes(Mondal and Mishra, 2017). The findings of this study are in agreement with those reported by Mondal and Mishra (2017). These findings, therefore, confirm that BMI affects both fat-free mass and the fat mass.


Table 3:Comparison of BMI, fat% and FFM between male and female subjects.

Parameters Male (Mean±SD) Female (Mean±Sd) t-test, p-value*
BMI (kg/m2) 25.14±4.61 24.53±2.27 0.5553
Fat% 23.65±5.55 32.89±3.06 <0.001
FFM (kg) 54.55±9.11 41.71±4.52 <0.001



This study has established that there is only a slight variation between the two methods BOD POD and TANITA in the determination of fat-free mass and fat is therefore clear that despite the different principles applied in the two techniques, the measurements remain the same. The variations in the analysis reported by the two methods have been attributed to the various equipment calibrators used and the possible errors.This study has also established that there is a relationship between BMI, fat-free mass and fat mass implying that the BMI affects the two parameters of health and obesity.


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