As with carbs, protein provides 4 calories per gram. What is freakin awesome about protein is that our body actually has to use energy to digest it. In other words, you actually burn calories when eating protein!
Let's say you ate100 calories of protein. Your body actually uses 20-30% of those calories just to digest it which means you only absorbed 70-80 of those calories! Mind. Blown.
Protein is made up of amino acids which are the building blocks of all of our body’s tissues, organs, muscles, hair, skin, enzymes etc.
Protein helps the absorption of nutrients, supports healthy metabolism, builds and supports muscles, helps to stabilize blood sugar, boosts energy and more. This is why, for most people, a diet sufficient in protein is highly recommended (especially as we age. Stay away, sarcopenia!)
Some good sources of protein include:
Beans
Lentils
Grass fed beef/ lamb
Grass fed dairy
Wild caught fish
Pasture raised eggs
Pasture raised poultry
For people with goals of building muscle and maintaining muscle, the amount recommended is usually about 1 gram per pound of lean body mass (or 1 gram per pound of ideal bodyweight.) But everybody and every body is different so please play around with the amount that feels good to you and always consult a physician.