Which nutrient class is considered to yield the most energy per gram?

Fat is considered to yield the most energy per gram among the nutrient classes. This is because fats provide approximately 9 calories per gram, which is significantly higher than the 4 calories per gram provided by both carbohydrates and protein. This high caloric content is due to the molecular structure of fats, which are dense energy sources, primarily composed of long chains of carbon and hydrogen atoms.

In contrast, carbohydrates and proteins serve various functions in the body beyond energy production. Although they contribute to caloric intake, carbs and proteins are less energy-dense compared to fats. Vitamins, on the other hand, do not provide energy; they function mainly as coenzymes or factors in metabolic processes and are essential for maintaining overall health, but they do not yield calories.

Therefore, the energy yield of fats makes them the most concentrated source of energy available in diet, highlighting their important role, especially in energy-restricted conditions or endurance activities where maximizing energy intake is crucial.