Which of the following is not a role of carbohydrates in the body?

Carbohydrates play a significant role in the body, primarily through providing energy, regulating blood sugar levels, and assisting with digestion. They are the body's main source of fuel, especially for the brain and during high-intensity workouts. Carbohydrates are broken down into glucose, which is then used for energy production.

In terms of regulating blood sugar, carbohydrates are essential because they impact how insulin works and help maintain stable glucose levels in the bloodstream. Foods rich in fiber, a type of carbohydrate, also assist with digestion by promoting gut health and regularity.

In contrast, while carbohydrates are essential for energy, they do not play a direct role in building muscle. Muscle synthesis is primarily driven by proteins and certain amino acids, which are the building blocks for muscle tissue. Therefore, carbohydrates' primary functions do not include muscle building, making this the correct choice.