Brown fat is a form of fat found in adipose tissue which releases heat rather than producing ATP on production of a lipolytic stimulus. It is due to the uncoupling of ATP synthase during oxidative phosphorylation. There is an increase in the rate of proton pumping to the mitochondrial intermembranous space. Also, there is increased passive movement backwards by a unique 'thermogenin' protein.
Brown fat is used by term neonates as a substrate for thermoregulation.
In adults, brown fat may be assimilated in preference to neutral fats as a means of minimizing adipocyte stores and countering obesity. It is stored in the subscapular and inguinal regions, and around the adrenal glands.
Last reviewed 01/2018