What influences the net combustible energy available in food?

The net combustible energy available in food is primarily influenced by the macronutrient's percentage of digestibility. This percentage refers to the proportion of energy that the body can extract from the food consumed after considering losses in digestion and metabolism. Different macronutrients (carbohydrates, proteins, and fats) have varying rates of digestibility, which directly affects the amount of energy they provide.

For example, carbohydrates and fats are usually more easily digestible and provide a higher amount of net energy compared to proteins, which are more complex and require more energy to digest. Understanding digestibility is crucial in nutrition because it determines how efficiently the body can use the energy from the food consumed, impacting overall health and performance.

While factors such as the amount of protein, cooking method, and food freshness can also affect the nutritional value and energy content of food, they do not directly change the intrinsic digestibility of the macronutrients involved, making the digestibility percentage the most significant influence on net combustible energy.