EvoElite Keto Carbohydrates: functions, classification, metabolism and food Functions in the organismCarbohydrates are the main energy source of the organism because during its digestion glucose is generated, this being the preferred fuel for the body's cells, since they degrade this molecule and ATP is produced, which is used in the various metabolic processes for the proper functioning of the organism. Glucose is mainly used by the brain, using 120 g per day, which represents the majority of the 160 g of glucose that the body needs daily.