Which macronutrient provides the most calories per gram?

Fats are the macronutrients that provide the most calories per gram, with each gram yielding approximately 9 calories. This high caloric density makes fats an essential source of energy, especially in dietary contexts where energy needs are significant.

In contrast, carbohydrates and proteins each provide about 4 calories per gram. Vitamins are micronutrients and do not provide calories, as they are essential for various biochemical functions in the body but do not serve as energy sources. This distinction highlights the importance of fats in nutrition and energy provision, making them vital for maintaining energy levels, especially for those with higher caloric requirements.