## 4 Discussion
[40] observed a weak correlation between the manual method and BIA-based estimates and recommended avoiding the BIA application for WHR calculation. Some studies also suggest that BIA calculations provide greater accuracy in estimating VFA when compared to abdominal CT scans, as opposed to manually measured WC [39; 43]. Additionally, WHR measured by BIA may better represent abdominal visceral fat. However, further research is required to determine the exact cause of the discrepancies between manual and BIA-calculated body composition metrics. The observed differences in agreement between the manual method and the BIA method for estimating WC or calculating WHR in males and females are undoubtedly due to differences in body composition and fat distribution. Females have proportionally more FM, and males have more FFM, which is biologically determined. This suggests that detailed imaging of adipose tissue distribution provides a more comprehensive assessment of metabolic risk associated with sex differences. [44; 45]. [PERSON] et al. [46] highlighted that sex and obesity-related differences must be considered when evaluating body composition. Our findings also revealed discrepancies between body composition assessments using bioelectrical impedance analysis (BIA) and air displacement plethysmography (ADP), with systematic biases being more pronounced in males. Such discrepancies may be attributed to variations in the interaction between measurement methods and the unique tissue characteristics of different populations. Specifically, bone and soft tissue composition may influence the accuracy of body fat estimation differently across sexes, as certain methods may either overestimate or underestimate body fat percentage (%BF) depending on the characteristics of the individuals being measured. Consequently, it is essential to explore how complementary technologies can be integrated to enhance the precision of body composition assessments. Combining different measurement tools could minimize bias and offer more reliable clinical decision-making, particularly when addressing sex- and obesity-related differences. Moreover, the accumulation of excessive adipose tissue is associated with hormonal activity. Estrogen promotes the accumulation of subcutaneous fat, which is more common in women, while testosterone is linked to the accumulation of visceral fat in men [47]. On a methodological note, the observed strong positive correlation between VAT and WC estimated by BIA confirms the need to refine algorithms for these parameters. The strength of our study includes the involvement of a relatively large sample size and the use of professional equipment and standardized measurement conditions. The limitations of the study can be related to the limited BMI range (18.5-29.99). To further improve the results of the study, a wider range of participants could be included with a higher BMI, above 29.99, to evaluate further how %BF results differ between measurement instruments. Secondly, there is a lack of additional body composition assessment techniques for comparison. For example, using DEXA would allow for a comparison with an established, highly accurate device. Similarly, including other BIA devices, given the variety available on the market, would have enhanced the study's practical significance. It is important to emphasize that there are no direct references in the scientific literature to methods for estimating waist circumference by InBody devices. InBody does not measure waist circumference directly but probably estimates it based on personal data and body composition results using mathematical models and algorithms, but it is not available to users. Thirdly, we did not investigate the multifactorial causes of excessive body mass or central obesity. Fourth, the study population consisted of relatively young individuals under 40 years of age. Fifth, ADP measurement was performed with TGV prediction using the BOD POD software.