Bioelectrical Impedance Versus Air-Displacement Plethysmography for Body Fat Measurements in Subjects with Abdominal Obesity: A Comparative Study

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.