Protein (meat, animal by-products, eggs)
is used primarily as a building material for growth and repair.
It is therefore not stored in the same way as fats and carbohydrates, unless it is over consumed where it is converted to fat and stored.
They are only used as an energy source in extreme cases (i.e. long endurance based events such as marathon, triathlon, cycling), whereby the amino acids are processed in the liver to provide energy.