Which type of nutrient is NOT a source of energy?

Water is the correct choice because it does not provide energy in the form of calories. While carbohydrates, proteins, and fats are all macronutrients that serve as energy sources for the body, supplying calories necessary for various functions and activities, water plays a crucial role in maintaining hydration and supporting various physiological processes without contributing to energy intake.

Water helps regulate body temperature, aids in digestion, and participates in biochemical reactions, among other functions. However, it does not contain calories or provide energy itself, making it distinct from the other nutrients mentioned, which are metabolized by the body to produce energy.