What is the energy yield from fats?

The energy yield from fats is 9 kcal/g. This value represents the caloric density of fat as a macronutrient in the human diet. Fats are the most energy-dense of the three main macronutrients, which also include carbohydrates and proteins. This high energy yield is due to the high concentration of carbon and hydrogen atoms in fatty acids, which provide more energy when metabolized compared to carbohydrates and proteins.

Carbohydrates yield about 4 kcal/g, while proteins also yield approximately 4 kcal/g. This significant difference in energy yield is why fats are utilized as an important energy source in both the diet and during extended physical activity or fasting states. Additionally, fats serve various essential functions in the body, including the absorption of fat-soluble vitamins and the provision of essential fatty acids.