To investigate the difference of visceral adipose tissue(VAT) area in different body mass index (BMI) patients.

Computed tomography (CT) was applied to measure VAT area, subcutaneous adipose tissue (SAT) area, and waist circumference (WC) in 1094 patients who met the inclusion and exclusion criteria. All patients were divided into four groups according to their BMI levels.Underweight group (BMI<18.5 kg/m², n=56), Normal weight group (18.5 kg/m²≤BMI<24 kg/m², n=444), overweight group (24 kg/m²≤BMI<28 kg/m², n=253) and obesity group (BMI≥28.0 kg/m², n=81). The difference of VAT, SAT and WC between the four groups was studied by rank sum test. Spearman correlation analysis method is used to understand the correlation between BMI and VAT, SAT, WC.

There were 834 patients with complete data in 1094 patients. There were 71 cases of cardiovascular disease, 114 cases of respiratory diseases, 349 of digestive diseases, 210 cases of urinary diseases, 19 cases of reproductive diseases, and endocrine system diseases in 29 cases. There was no significant difference in the VAT content of patients with different BMI above six systemic diseases (P>0.05). Four groups of patients included underweight group (n=56), normal weight group (n=444), overweight group (n=253) and obese group (n=81). The rank sum test shows, there were significant differences in VAT、SAT and WC between the four groups (P<0.01). The results of inter-group comparison showed that the SAT content of the four groups was in the obese and overweight group > normal weight group > underweight group (P<0.01). VAT area and WC in inter-group comparison shows, overweight and obesity group > normal weight group > underweight group (P<0.01). However, there was no significant difference between obesity and overweight (P>0.05). The inter-group correlation analysis showed, in normal and overweight groups, positive correlation between BMI and VAT (r=0.402 and 0.195, P<0.05). A correlation was not found in the underweight and obese groups (P>0.05). There was a positive correlation (r=0.296) between BMI and SAT area in normal weight group (P<0.05), but not in the other three groups (P>0.05). The positive correlation between BMI and WC was found in normal and overweight groups (r=0.199 and 0.144, P<0.05), but not in the underweight and obese groups (P>0.05).

As a common clinical index of obesity, there is a limited correlation between BMI and imaging obesity indicators. The BMI level in a certain range is helpful to speculate the visceral fat content. When the weight is too light or obesity reaches a certain degree, the BMI level may not be used to speculate the severity and distribution characteristics of visceral fat.