What is the energy yield of protein?

The energy yield of protein is indeed 4 kcal/g. This value is based on the fact that proteins, which are made up of amino acids, can be utilized by the body for energy when carbohydrates and fats are not available. Each gram of protein contributes 4 kilocalories of energy when metabolized.

This yield is important for understanding macronutrient metabolism and dietary recommendations. In the context of a balanced diet, while protein can offer energy, its primary role is to support growth, repair tissues, and facilitate numerous metabolic processes rather than serve as a major energy source.

Other options such as 7 kcal/g, 9 kcal/g, and 2 kcal/g do not align with the established scientific data on protein metabolism. Fats, for example, yield 9 kcal/g, which is why they are a more concentrated energy source. Carbohydrates, like proteins, yield 4 kcal/g, and alcohol provides 7 kcal/g. Understanding these distinctions is crucial for effective nutritional planning and dietary therapy.