The main function of carbohydrates is for energy in the body. Carbohydrates are the preferred fuel for the body, so you want a majority of total calories coming from carbohydrate. In the absence of carbohydrates, protein is broken down to provide needed energy - which could lead to a protein deficiency, and loss of lean body mass. In cases of extreme exercise, starvation or high protein, low carbohydrate diets, a deficiency may occur. If intake of carbohydrate is in excess of total energy needed by the body, the excess carbohydrate will be stored as fat. It is best to try to consume more complex carbohydrates, and less simple sugars.

recommendation: there is no set recommendation for carbohydrates, but an intake of at least 50-100 g per day is needed. It is recommended that 50-60% of total calories come from carbohydrate, with no more than 10% of those calories coming from simple sugars.
foods in (complex sources): whole grains, breads, pastas, rice, cereals, starchy vegetables such as potatoes, corn, lima beans, kidney beans, and baked beans. Simple sugars include sugar, candy, high fructose corn syrup, soda, jelly, and honey.

Any of a group of chemical compounds, including sugars, starches, and cellulose, containing carbon, hydrogen, and oxygen only.