Fig. (1) Abdominal Obesity index (ABOI) and central obesity. The upper body cavity cylinder can be divided into the abdominal segment and the thoracic segment. C1 and C2 represent the circumferences of the thoracic segment and abdominal segment, respectively. To simplify the calculation of volumes, the heights (h) of the thoracic segment and the abdominal segment are considered the same. The volume of thoracic segment = h∙2πr2 in which r = ½C1 and the volume of the abdominal segment = h∙2πr2 in which r = ½C2. = ABOI = [C2]2/[C1]2. Generally, the larger the ABOI is, the more severe the central obesity is.