ESR2 and obesity due to melanocortin 4 receptor deficiency: In the present study, by using ERβ knock out (ERβ−/−) mice and wild type (WT) mice with obesity induced by consumption of a Western diet (WD), we found that ERβ regulates the number of CLS in subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) as well as activation of macrophages in CLS.