FGF21 and obesity due to melanocortin 4 receptor deficiency: Previous studies have demonstrated that numerous molecules possess the potential of combating obesity, including β-adrenergic agonists CL-316,243 [36] and mirabegron [37], cytokines fibroblast growth factor-21 (FGF21) [38], irisin [39] and bioactive ingredients resveratrol [40], berberine [19], etc. In this paper, we found another natural product, Rut, exerts a positive effect on HFD-induced weight gain by regulating thermogenesis in brown and beige adipocytes.