Why do you need whole milk for the chemical composition of milk?

Milk is made up of protein, fat and sugar. Protein is the medium of foaming, and when the air is pumped into the milk, the protein forms a thin film around the air, wrapping the air to form bubbles. Fat inhibits and destroys the foaming process, although whole milk produces softer foam than skimmed milk, and milk that is fortified (adding protein back to the milk) compared with unfortified milk. It will be easier to blister, and then the volume of expansion will be larger, which is why low-fat milk will add protein. Because there is a lot of protein and less fat, and after blistering, it has a larger volume.