Water is involved in all of the following EXCEPT:

Water plays a vital role in numerous bodily functions, but it does not provide calories. It is essential for digestion, as it helps break down food and absorb nutrients. When it comes to body temperature regulation, water is crucial because it helps maintain a stable internal temperature through processes like sweating and respiration. Nutrient transportation relies heavily on water, as it is the primary medium through which nutrients are dissolved and moved throughout the body.

In contrast, the option related to being a source of calories is correct because water contains no calories. In nutrition, calories refer to energy derived from macronutrients like carbohydrates, proteins, and fats, none of which are present in water. Thus, while water supports many physiological processes critical for health, it does not contribute energy in the form of calories.