TGFB1 and obesity due to melanocortin 4 receptor deficiency: In summary, we have uncovered a core mechanism underlying AT fibrosis by which the Hippo pathway orchestrates a cellular transition from adipocyte to myofibroblast when the pathway is inactivated, and a functional shift of adipocytes from energy storage to ECM remodeling upon its inhibition during obesity, both in close coordination with TGFβ signaling.