Obesity is a disorder with an increasing prevalence, associated with cardiovascular and metabolic pathologies. The amount and the distribution pattern of adipose tissue must be considered when managing this disease. Abdominal obesity carries a higher risk of developing obesity-related comorbidities. Body composition methods allow an objective diagnosis and follow-up in obese patients. Although bioelectrical impedance (BIA) is a practical, affordable, and widespread technique to assess body fat percentage (%BF), its accuracy has often been questioned. Therefore, the present study aimed to determine BIA’s accuracy in subjects with abdominal obesity compared to air-displacement plethysmography (AP) as the reference method. Measurements with both body composition techniques were performed on 80 subjects (41 men and 39 women) with a large range of body mass indexes (BMIs). Abdominal obesity, diagnosed as a waist-to-height ratio (WHtR) above 0.5, was present in 28 of them. Agreement between methods was analyzed using t-tests, correlation, and Bland–Altman plots. Compared to AP, BIA underestimated %BF by 3.07 ± 5.81% (CCC = 0.82) in the entire study group. The agreement was comparable in subjects with and without central obesity (2.97 ± 6.21% and 3.26 ± 5.1%, respectively). The changes in body shape geometry due to different adipose tissue distribution patterns only marginally affected BIA’s determinations.

Bioelectrical impedance analysis (BIA) is a widely used and an easy-to-apply method for determining body composition. However, its accuracy depends on population-specific equations. The aim of the present study is to identify the most appropriate fat-free mass (FFM) prediction equation for an Eastern European population using air-displacement plethysmography (ADP) as the reference method. The study group included 101 Caucasian subjects (56 women and 45 men) with an average body mass index (BMI) of 25.37 ± 5.45 kg/m². One set of FFM_BIA values was automatically calculated with the analyzer (Maltron BioScan 920-2), and four others were computed using the published equations of Kyle, Kanellakis, Heitman, and Deurenberg. The results were compared to FFM_ADP values measured using a BOD POD Gold Standard Body Composition Tracking System by Bland–Altman analysis. The smallest bias was obtained with the equation by Deurenberg, which underestimated FFM by only −0.22 ± 4.52 kg. The largest bias was obtained with the equation by Kyle (5.92 ± 4.73 kg), followed by the formula of Kanellakis (3.04 ± 4.65 kg). The equations by Heitman and the Maltron inbuilt formula overestimated FFM by 2.15 ± 4.27 kg and, respectively, 1.95 ± 4.3 kg. Although Maltron’s automatically generated values were very strongly correlated with ADP results (CCC = 0.93, SEE = 4.7), the formula by Deurenberg provided the most reliable estimates in the studied population.