At the cellular level, metabolism is governed by the mitochondria which provides 90% of our energy in the form of ATP. This energy is synthesized within oxidative phosphorylation, which consists of 2 entities (the respiratory chain and ATP synthase) and which allows the conversion, in water and ATP, of the reduced equivalents resulting from dehydrogenation reactions (and Decarboxylation) of energetic nutrients, in the presence of dioxygen (O2) and ADP, according to chemosmotic coupling theory . The decoupling of oxidative phosphorylation may be involved in involuntary weight loss. The work of Romestaing et al. Showed that weight loss following the development of a steatosis was associated with a decrease in the ATP / O2 ratio . Mitochondrial dysfunctions could therefore have a direct effect on the protein degradation observed during cancer cachexia. In addition, systemic inflammation caused by the development of the tumor can also affect mitochondrial bioenergetics.