When the homeostasis senses that your too cold, it sends signals to your muscles that make your shiver and create warmth. This is called maintaining the homeostasis.
Because fatty acids are also known as lipids and lipids are used for long term energy, and proteins are also used for energy. I think that this makes them essential because they are able to keep a healthy amount of energy in their system and without them they would not be able to do so.
