Mitochondria play a central role in cellular function and metabolism by coupling cellular respiration to the production of ATP.
However, this coupling is not perfectly tight. Approximately 20% of the standard metabolic rate in mammals is due to a leak of protons across the mitochondrial inner membrane (basal proton leak) in a manner that uncouples cellular respiration from ATP production, thereby generating heat. Animal and human studies indicate that the metabolic function develops primarily after birth when the newborn is first exposed to nutrition via the gastrointestinal tract and that the composition of the gut microbiota influences body composition, digestion and metabolic homeostasis. [The Journal of Nutritional Biochemistry Volume 26, Issue 11, November 2015, Pages 1136-1146]