One potential mediator in coupling obesity to T-cell immunity is the mechanistic target of rapamycin (mTOR) signaling pathway: The mTOR complex is a signal integrator for nutrients, growth factors, and intracellular energy levels, and the chronic activation of mTOR signaling during obesity promotes lipid synthesis and adipocyte differentiation [36]. Here, MTOR is linked to obesity due to melanocortin 4 receptor deficiency.