How many calories are there in a gram of protein?

A gram of protein provides 4 calories. This is an established nutritional standard that reflects the energy yield from protein when metabolized in the body. Proteins, which are made up of amino acids, serve as a crucial source of energy, among other functions such as building and repairing tissues. The caloric content of macronutrients is important for understanding dietary energy intake: carbohydrates also yield 4 calories per gram, while fats provide a higher amount at 9 calories per gram. This distinction helps in formulating balanced diets and understanding the energy contributions of different food groups.