Additional variables may exist that influence dietary energy needs under unusual conditions. Gross energy less fecal and urinary wastes energy. Used mostly in the case of birds. Productive Energy-Net energy less the energy required to maintain the body's metabolic functions. Some organs require CHO to function.
Excess energy is stored as body fat regardless of the original source of energy.
Proteins provide remaining energy, only after meeting the requirements for dietary amino acids. Most abundant organic substances in nature. All CHO are converted to glucose before being metabolized. Primary purpose for CHO is to store energy. Destination of Glucose in animals.