What mechanism does the body employ to deal with excess protein intake?

The body manages excess protein intake primarily by converting surplus amino acids into fat once it surpasses the absorption capacity. When protein is consumed, the body utilizes amino acids for various essential functions, including muscle repair, hormone production, and enzyme synthesis. However, there is an upper limit to how many amino acids the body can utilize effectively for these functions at any given time.

Once protein intake exceeds what is necessary for these immediate needs, the body deaminates the excess amino acids, which involves removing the amino group. The remaining carbon skeleton is then transformed into substrates that can enter metabolic pathways. If there is still an abundance of these substrates, they will ultimately be converted into fatty acids and stored as fat in adipose tissue. This process allows the body to maintain energy balance and ensure that it can adapt to varying intake levels while still meeting critical protein demands.

Other mechanisms mentioned, such as immediately excreting unused protein or converting all excess into energy, do not occur in the same comprehensive way as the conversion to fat after the absorption limits are reached. Protein is not stored as glycogen because glycogen is primarily derived from carbohydrates, and while some nitrogen is excreted via waste products like urea, it does not account for the excess beyond immediate utilization