92, 829-839, March 20, 1998.
Obesity is the result of a consistently greater intake of energy, i.e. food, than output of energy.
To shift the energy equilibrium back toward a balanced state, energy dissipation can be increased to match energy intake. Energy expenditure occurs through physical activity, basal metabolic rate, or adaptive thermogenesis. Adaptive thermogenesis is a part of the sympathetic nervous system's attempt at maintaining homeostasis during changing environmental conditions. Typically in response to cold exposure or excessive caloric intake, adaptive thermogenesis increases the production of mitochondria and the rate of ATP production in order to create more heat. UCPs facilitate proton transport within the mitochondrial membrane, by reducing the hydrogen ion gradient associated with oxidation occurring in the electron transport chain.