Despite what past diet fads may have led us to believe, carbohydrates are our bodies' preferred source of energy. All carbohydrates share the same fate of being broken down into sugars that are used to fuel your brain and body. So what's the difference then between simple and complex carbohydrates?

It's a matter of numbers. Simple carbohydrates, which are already sugars, contain a smaller number of units to be broken down. They're used up quickly, providing a burst of energy that isn't lasting. Complex carbohydrates, which include starches and fiber, consist of many more units. They take longer to be broken down into sugar, and they fuel your body slowly and evenly over a longer period of time.

Does it really matter which kind of carbs we consume, as long as we keep our bodies fueled? Yes, it does. Simple carbohydrates include table sugar and sweeteners commonly added to processed foods, including honey and fruit juice concentrate. These sugars are highly concentrated, containing lots of carbohydrates and calories in tiny packaging, but few nutrients besides the sugars themselves. They empty quickly from your stomach, so that before long, you're hungry again.

Complex carbohydrates, which include whole fresh fruits, beans, bread, rice, and vegetables, like potatoes and corn, are diluted, making them bulkier. It takes fewer calories to satisfy your hunger. A cup of blueberries contains the same amount of calories as a tablespoon of sugar. And if the complex carbs you consume are unprocessed--for instance, you consume wheat bread rather than white--then they provide you with lots of fiber and nutrients.  Fiber-rich complex carbs also last longer in your stomach, so that you're satiated longer.