Energy deficit is clinically relevant for critically ill patients: yes

Excerpt

Survival mechanisms have evolved for thousand of years to optimize vital energy-dependent functions at the expense of substrates stored in lean and fat tissues. A phylogenic analysis of mammalian biology supports the concept that human beings challenged by life-threatening conditions have been programed for energy autonomy for a few days only, as the absence of hydration for 4–5 days defines the survival limit. Beyond this limit, both water and some energy are needed for further survival and functional recovery. In addition, only the strongest and youngest individuals were likely to survive, as the ultimate goal was the reproduction of the species. Energy deficit promotes proteolysis and lipolysis to fuel the mandatory gluconeogenesis, which rapidly deteriorates most of the vital body functions (e.g., muscle strength, physical mobility, thermic control, immune response, etc.). This deficit induces auto-cannibalism, a short-term, life-saving, genetically driven mechanism, but also a condition compromising recovery and increasing morbidity and ultimately mortality [1, 2]. …