Thermogenesis is the process of heat production. Non-shivering thermogenesis usually occurs in brown adipose tissue (brown fat) that is present in newborn and hibernating mammals. It is a process where substances such as free fatty acids (derived from triacylglycerols) remove purine (ADP,GDP...) inhibition of thermogenin (uncouping protein-1) which causes an influx of H+ into the matrix of the mitochondria and bypasses the ATP synthase channel (also uncoupling oxidative phosphorylation) therefore dissipating as heat rather than producing ATP from ADP.