What Is a Carbohydrate?

Technically speaking, a carbohydrate is a compound made up of carbon, hydrogen, and oxygen. The most basic carbohydrates are called simple sugars and include honey, jams, jellies, syrup, table sugar, candies, soft drinks, fruits, and fruit juices. Glucose (also called dextrose) is a common simple sugar found in fruits, honey, and vegetables. It is also the substance measured in blood. (In other words, blood sugar equals blood glucose.) They are relatively small compounds. When several of these simple sugars are linked together, they form more complicated molecules known as complex carbohydrates.

Complex carbohydrates that come from plants are called starch and are found in quality foods such as grains, vegetables, breads, seeds, legumes, and beans. Whether it's a handful of jelly beans or freshly sliced whole grain bread, it's all carbohydrate!

Sweet Satisfaction: The Lowdown on Simple Sugars

So your favorite sugary sweets are classified as carbohydrates—and you're supposed to eat a lot of carbohydrates—so it's okay to load up on gummy bears and licorice, right?

Not a chance. Here's why: the quality of your carbohydrates matters tremendously. Simple sugars such as candy, sodas, and sugary sweeteners found in cakes and cookies offer little in the form of nutrition except providing your body with energy and calories. These foods are literally "empty calories" —calories with no nutritional value. In moderation, simple sugars are perfectly fine (and, I admit, yummy), but people who consistently load up on the sweet stuff often find themselves too full for, or uninterested in, the healthy foods their bodies require. The end result is too much sugar and not enough nutrients.

Where Do Fruits and Fruit Juices Fit In?

There are some exceptions to the “no sugar” rule. For example, fruits and fruit juices contain fructose (a natural simple sugar) and provide several vitamins and minerals. Eating fresh fruit or drinking 100 percent fruit juice is far from pumping “empty calories” into your system. When you can, choose whole fruit over fruit juice: you get the same nutrients, as well as more complex carbohydrates and fiber.

As you can see in the following table, juice and cola both contain simple sugars, but juice provides a lot more nutrition.

All About Complex Carbohydrates

Now that you know what you shouldn't load up on, let's take a look at the foods you should eat. By now, you should be clued-in to which foods are rich in complex carbohydrates (pasta, grains, breads, cereal, legumes, and vegetables). Although they're actually made from hundreds—or even thousands—of simple sugars linked together, they react quite differently inside your body. After you ingest a complex carbohydrate (or starch), several enzymes break it down into its simplest form, called glucose.

Glucose is the simple sugar that your body recognizes and absorbs. All types of carbohydrate (simple and complex) must be broken down and converted into glucose before your body can absorb and use it for energy.

If all carbs wind up as glucose, why can't we just eat simple sugars? I've already touched on the first reason. Many simple sugars are nutrition zeroes, whereas complex carbs often provide phytochemicals, vitamins, minerals, and even fiber, depending on the food.

In fact, your best complex carbs include vegetables and whole grains (not the white, refined stuff). Check out this comparison: a large baked sweet potato (high-quality, complex carb) versus a 20-ounce bottle of cola (simple carb). Although both provide about 280 calories, that's where the similarity ends. The sweet potato supplies potassium, magnesium, vitamin A, folic acid, vitamin C, and significant fiber, along with several other vitamins and minerals. And the cola—you probably guessed—provides zilch. Just plain sugar (18.5 straight teaspoons!). What's more, the sweet potato provides you with a fuller and more satisfied feeling. As you can see, eating complex carbs certainly does make a difference, even though it all ends up as glucose.

Another reason to choose complex carbohydrates is that the glucose created during digestion gets released into your blood more slowly. Simple carbohydrates are already broken down—they go straight into the blood, resulting in what is unofficially known as the “sugar rush”—whereas complex carbohydrates are larger molecules that must be broken down. As your body processes complex carbs, small glucose molecules are released into the blood over an extended period of time. This helps to regulate blood-sugar levels, especially in people who may have problems with their blood sugars (for example, people with hyperglycemia, hypoglycemia, or diabetes mellitus).

For the best regulation of problematic blood-sugar levels, choose carbohydrates that supply soluble fiber, including oatmeal, apples, sweet potatoes, beans, artichokes, grapefruits, squash, peas, brussels sprouts, and oranges.

How Much Carbohydrate Should You Eat?

As mentioned earlier, no less than 40 percent of your diet should consist of carbohydrates, specifically, complex carbohydrates. Most athletes and growing children and adolescents will need far more carbs than this, though. But no matter how high or low you go—always make the bulk of your carbs healthy ones.

Excerpted from The Complete Idiot's Guide to Total Nutrition © 2005 by Joy Bauer. All rights reserved including the right of reproduction in whole or in part in any form. Used by arrangement with Alpha Books, a member of Penguin Group (USA) Inc.

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