Carbs help you get energy to keep going the whole day and won't feel tired
What Is The Purpose Of Carbohydrates?
The basic function of carbohydrates is to provide us with energy. Carbohydrates that are fibrous in form also help keep our intestinal tract healthy and in good working order.
I think it is mainly to give us energy even though fats provide us with double the energy given by both proteins and carbohydrates we eat carbohydrates for energy!