###### Abstract  
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 \(\pm\) 5.81% (CCC = 0.82) in the entire study group. The agreement was comparable in subjects with and without central obesity (2.97 \(\pm\) 6.21% and 3.26 \(\pm\) 5.1%, respectively). The changes in body shape geometry due to different adipose tissue distribution patterns only marginally affected BIA's determinations. b +
Footnote †: journal: Applied sciences  
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The body mass index (BMI) is the most commonly used and widely accepted method for screening obesity [5]. Originally proposed by [PERSON], it is defined as the ratio of the weight to the square of the height. A BMI higher than 25 kg/m\({}^{2}\) classifies an individual as overweight, while one above 30 kg/m\({}^{2}\) classifies the individual as obese, with lower cut-offs proposed for Asian populations [6]. Although the BMI is simple, cheap, and widely applicable, it has the disadvantage of not being able to differentiate between fat and lean tissue content. This aspect is of major importance in patients with edema or malnutrition, as well as in individuals with age-related muscle loss, low body fat, or higher muscle mass [7]. Cardiometabolic risk is influenced by both the amount and distribution of excess dysfunctional adipose tissue. Individuals with a higher percentage of adipose tissue within the abdominal region have a greater cardiometabolic risk. Therefore, it is important to assess both the body fat percentage (%BF) and the obesity phenotype. Based on the adipose tissue amount and its distribution, obesity is divided into two categories: metabolically healthy and metabolically unhealthy. The first one is associated with a lower inflammatory profile, better renal function, higher concentrations of adiponectin, good nutritional status, and reduced liver fat [2;8]. In contrast, metabolically unhealthy obesity is more strongly associated with cardiovascular and metabolic disorders and is characterized by a greater accumulation of adipose tissue in the visceral region compared to subcutaneous fat [9]. In order to differentiate between the two types of obesity, several anthropometric parameters can be used, such as the waist circumference (WC), hip circumference, body adiposity index, waist-to-hip ratio, waist-to-height ratio (WHtR), neck circumference, and skinkold thickness [10]. According to WHO criteria, abdominal obesity is diagnosed when the WC is equal to or greater than 102 cm in men or 88 cm in women. Different cut-offs have been proposed by the International Diabetes Federation: 90 cm for men and 80 cm for women [11].