Which of the following is not a function of proteins in the body?

The primary role of proteins in the body encompasses building and repairing tissues, supporting immune function, and transporting molecules. While proteins are essential for numerous metabolic processes, they are not considered a primary energy source. The body's main energy sources are carbohydrates and fats.

Proteins do contribute to energy production, particularly during times of fasting or when carbohydrate and fat stores are insufficient. However, this is not their primary function; they are more aligned with structural and regulatory roles rather than serving as a go-to energy source. Thus, stating that proteins serve as a primary energy source is inaccurate, reinforcing why this choice is not aligned with the fundamental functions of proteins in the body.