Final answer:
To use amino acids as a fuel, the nitrogen attached to the amino acid must be removed through the process of deamination. The resulting ammonia is converted into urea and excreted.
Step-by-step explanation:
In order to use amino acids as a fuel, the nitrogen attached to the amino acid must be removed. This process is known as deamination. The amino group is converted into ammonia, which is then processed and excreted as urea in mammals. Urea is the principal waste product of protein metabolism and is excreted in urine.