UCP1 and obesity due to melanocortin 4 receptor deficiency: In metabolic disorders such as obesity and metabolic syndrome, quercetin can enhance WAT browning and brown adipose tissue (BAT) activation due to activation of β3-adrenergic receptor (β3AR)/PKA/AMPK/PPARγ/peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) pathways, by this means inducing expression of uncoupling protein 1 (UCP1) and ABCA1 to promote adenosine triphosphate (ATP) and inhibit fat accumulation [68–70].