Calories Per Gram Carbohydrates . . . 4 Protein . . . 4 Fat . . . . . 9 Current dietary guidelines recommend obtaining 55 to 60 percent of your calories from carbohydrates, especially complex carbohydrates. Carbohydrates are an important energy source, fueling the central nervous system and muscles during physical activity.
Sugars are simple carbohydrates because they consist of one or two sugar units.
Sugars occur naturally in fruits, vegetables, milk and other foods, as well as in a refined state, such as table sugar or sucrose. Complex carbohydrates are found in grain foods, fruits and vegetables. The most common grain foods are wheat, rye, barley, oats, corn and rice. Whole-grain foods contain many different mixtures of carbohydrates and large molecules present in all plant foods. These are still under investigation for their contributions to the diet.