Among the options listed, the nutrient that is not used as a source of energy by the body is vitamins.
Here's a brief overview of the other nutrients mentioned:
- Proteins: While primarily used for growth, repair, and maintenance of tissues, proteins can also be used as an energy source, especially when carbohydrate availability is low.
- Carbohydrates: This is the body's primary source of energy.
- Fats: Fats are also a significant source of energy and are used for long-term energy storage.
Vitamins, on the other hand, are essential for various biochemical processes and help in the metabolism of macronutrients, but they do not provide energy themselves.