Figure 1. Regulation of cellular bioenergetic efficiency under conditions of nutrient excess.
In the balanced state fuel/nutrient “supply” is sufficient to sustain energy (ATP) “demand”. Under this condition “waste” or inefficiency in the form of heat is minor. Nutrient excess, characterized by “excessive supply” in the absence of a parallel increase in “demand” represent a situation were the energy required to satisfy ATP demand is lower than the available energy. This is compensated for by adding an energy sink that does not involve ATP synthesis. This component is inefficiency/waste in the form of heat. The major mechanism for inefficiency/waste in the form of heat is mitochondrial proton “leak”. This mechanism can slow down nutrient accumulation and prevent the development of reductive stress (accumulation of NADH), and ROS production.