Protein's carbon component can enter the TCA cycle as two-carbon or sometimes four-carbon pieces for energy production.

“the protein part is a little more complicated we can probably skip it okay so you end up with these two carbon units but we're worth just sort of noting josh that protein really the primary role of protein is actually the nitrogen side which we're kind of putting into these amino acids that are building blocks it's really less of an energy substrate but it does have that carboxylic acid on it that still has to go through this cycle and be exhaled”