If you're eating less fat — as most people are trying to do — it's likely you're eating more of something else to fill the void. That something is probably carbohydrate.

But what kind of carbohydrate? Bagels? Pasta? Sugary snacks? Or perhaps whole grains along with more fresh fruits and vegetables?
The carbohydrate choices you make are significant, because carbohydrates — especially those from whole-grain sources — can play an important role in healthful eating and disease prevention.

Your body's fuel

Carbohydrates are the fuel your body needs to function. Your brain, for example, primarily uses a carbohydrate as its source of energy.

Most of the carbohydrates are plant based. Grains, vegetables, fruits and legumes (such as peas and beans) are typical sources. Dairy products are the only animal-based foods with significant carbohydrates.

There are three types of carbohydrates — sugars, starches and fiber. Sugars and starches provide 4 calories per gram of carbohydrate. Fiber has no calorie value because it's not absorbed. Instead, it helps to move things more easily through your digestive system and can slow the absorption of calories. For comparison, fat has 9 calories per gram.

Simple and complex

At the base of all carbohydrates are sugar "units." Depending on how many there are and how intricately they're connected, these units determine if carbohydrates are:

• Simple (sugars) — These are built from single or double sugar units. Simple carbohydrates are found in milk, fruits and some vegetables. However, the main sources in most people's diets are added sugars and processed foods. Table sugar is a pure form of simple carbohydrate.
• Complex (starches and fibers) — These consist of combinations of chains of sugar units. In comparison to simple carbohydrates, it takes more steps for your body to break down starches. Fiber is so complex it's not even digested.

Complex carbohydrates can be found in grains or foods made from grains, such as bread, cereal and pasta. Potatoes and some vegetables, such as corn, are high in starch.

The case for high fiber

More and more attention is being directed at the important role certain complex carbohydrates play in your diet. Of special interest are foods that are high in fiber and nutrient rich, such as whole grains, vegetables and legumes.

The reason? High-fiber carbohydrates are digested more slowly and, as a result, your blood sugar level doesn't rise as quickly. By comparison, low-fiber carbohydrates are digested faster, so they raise your blood sugar rapidly.

Rapid rises in blood sugar can cause your body to respond by producing higher levels of insulin, a hormone that helps regulate blood sugar levels. Over time, this can lead to health problems.

How to get your 'carbs'

Nutrition experts generally agree that 55 percent to 60 percent of your total daily calories should come from carbohydrates. And because carbohydrates aren't equal, there's growing evidence that you should be choosy about those you eat.

With simple carbohydrates, it's important to drink milk and juice and eat the right amount of fruit. But table sugar and other sweeteners provide unwanted calories and in large amounts can have health risks.

With complex carbohydrates, avoid loading up only on low-fiber, starchy carbohydrates — such as potatoes and processed grains like white rice, pasta and white bread. These carbohydrates are more rapidly converted to simple sugars by your body.

Instead, try to eat plenty of complex carbohydrates that include a good dose of fiber. In particular, legumes, whole grains and whole-grain foods appear to offer real health benefits.

Round that out with the recommended servings of fruits and vegetables for a complete and healthful mix of dietary carbohydrates.

Ways to get carbohydrates

The Food Guide Pyramid recommends that you eat a variety of carbohydrates daily from the following food groups:

• 6 to 9 servings of grains
• 3 to 4 servings of vegetables
• 2 to 3 servings of fruits
• 2 to 3 servings of dairy products

Easy ways to eat more high-fiber carbohydrates include:

• Snacking on dried fruit
• Making hearty soups with legumes as a base
• Switching to whole-grain breads
• Switching from white rice to brown (or mix in some wild rice)