Dear student,
Amino acids are building blocks of protein, humans take good amount of protein in their diet which is metabolised and is broken into amino acids. The excess amount of amino acid is not stored in the body and thus, Catabolized (metabolised)
Catabolism is a type of metabolism in which breakdown of complex molecules takes place to release energy.
As end product of metabolism of amino acid, CO2 + energy is released. This process takes place via many metabolic pathways like TCA cycle and Respiratory chain.
Regards