Why can't amino acids be stored in the body?

The fact that we cannot “store” them is not a correct description. It might be better to describe it as “we are unable to store excess of amino acids for later use. read more

Also, the excess amino acid pool would have to contain all the specific amino acids necessary to make the protein. Suppose your diet contains an excess of all the essential amino acids except lysine. Now you can’t make the storage protein. read more

but, we can't just store huge amounts of ammonia because it's toxic. sugars and fats aren't toxic, so we can store them. because of this, our body either quickly utilizes excess ammonia to make nitrogenous compounds like amino acids and nucleotides, or it excretes it via Urea in our urine. but there are some AAs that we cannot create ourselves. read more

Amino acids are there in the body but not in excess. Osmolarity. The same reason why excess glucose molecules are stored as glycogen. Similarly, excess fatty acids are tucked away as TAG. read more