Previous studies have shown that active brown adipose tissue (BAT) is present in adults and may play important roles in material and energy metabolism. However, most of these studies were tumor-based populations and retrospective study. Due to the large amount in our cohort, the investigators are able to promote a cross-sectional study of the incidence and factors of BAT in adult chinese. In addition, the investigators can analyse the metabolic profiles in healthy adults with active BAT.