The much-maligned carbohydrate is actually needed in your daily diet because it is the main source of fuel for your body. Carbohydrates are neither all good nor all bad. It is true that some are healthier for you than others. Carbohydrates should compose 45 to 65 percent of your daily calories. There are three main types of carbohydrates: sugars, starches and fiber, which are then classified as simple or complex carbohydrates.
Breakdown of Carbohydrates
Chains of sugar molecules comprise the different carbohydrates. During digestion, carbohydrates are broken down into their component sugars and converted to glucose, which is transported across cell membranes to get into the bloodstream. Most of the glucose is used for energy right away, but any excess is moved to the liver and muscle cells to be stored as glycogen for use in-between meals. Once the body has enough glycogen saved for energy, the excess is then stored in fat cells.
"Good" Carbohydrates
In general, the "good" carbohydrates are the starches, or complex carbohydrates. Complex carbohydrates are composed of long chains of sugar molecules. They take longer to be broken down, so they enter the bloodstream and raise blood sugar levels more slowly. They also take longer to be converted into fat. Healthy complex carbohydrates include whole grains, like whole-wheat bread, pasta, steel-cut oatmeal, brown rice, barley, bulgur, and buckwheat, along with legumes such as peas and beans. Beans, such as kidney beans and black beans, have the added benefit of providing protein to the diet. Most of these foods also contain plenty of dietary fiber. Fresh fruits and vegetables are also complex carbohydrates and an excellent source of dietary fiber.
"Bad" Carbohydrates
Simple carbohydrates are the "bad" carbohydrates. They are comprised of small molecules of sugar that are broken down and enter the bloodstream quickly, rapidly raising blood sugar. They provide an immediate burst of energy, but a few hours later cause blood sugar levels to drop. Many refined, or highly processed, foods like white breads and commercial baked goods provide little nutrition but are high in calories, the reason simple carbohydrates increase the risk of obesity and diabetes. Simple carbohydrates include foods containing high-fructose corn syrup, brown sugar, cane sugar, honey and fructose, lactose and sucrose. Fruits do contain fructose, a simple sugar, but are also packed with vitamins, minerals and fiber. The Centers for Disease Control and Prevention advises eating fresh and frozen fruits, and avoiding fruit juices that contain a lot of added sugars.
Significance
Overall, complex carbohydrates are called the "good" carbohydrates because they are healthier for you. They are often lower in calories, which aids in weight management. Complex carbs typically have more nutrients than simple carbohydrates, and the fiber they contain will help keep you feeling full longer. All carbohydrates are not the enemy: Choose healthy, complex carbohydrates along with a balanced diet containing protein, fats and dairy, and you can't go wrong.
References
- Harvard School of Public Health: Good Carbs Guide the Way
- U.S. Department of Health and Human Services: Carbohydrates
- Centers for Disease Control and Prevention: Carbohydrates
- Merck Manuals Online Medical Library: Carbohydrates, Proteins and Fats
- MedlinePlus: Carbohydrates
- The Diet Channel: Good Carbs vs. Bad Carbs
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