Here's why:

* Egg white is almost entirely composed of proteins, particularly albumin.

* Lipids (fats) are found in the yolk of the egg, not the white.

* Proteins are large, complex molecules made up of amino acids.

* Lipids are fats, oils, and waxes. They are not made up of amino acids.

So, while egg white does contain some trace amounts of lipids, it is primarily a protein source.