Go to a dinner party these days and you’ll probably meet both carbohydrate boosters and carbohydrate bashers. For carbohydrates have become a battleground in debates about healthy eating. They’re what you’re supposed to fill up on when you cut down on fats, says one side of the table. Or they’re what’s making Americans fat, according to the other side. Yet most people don’t really know what carbs are.
Carbohydrates include all the sugars and starches we eat. Carbohydrates can be confusing because they are found in so many foods. All of the following, for example, are rich sources of carbohydrates: orange juice, beans, cereal, milk, pears, berries, bread, apple pie, popcorn, pasta, cookies, biscuits, green peas, muffins, honey and sweet potatoes.
As you can see, most carbohydrates come from plant-based foods—fruits, vegetables, grains and legumes. Dairy products are the only animal-derived foods that contain lots of carbohydrates. Carbohydrates are the main energy source for the body. They supply 4 calories per gram, about the same as protein. Fat has more than twice as many calories (9 per gram)—which is one reason for its bad reputation. Alcohol also has more calories (7 per gram). Carbohydrates comprise the main source of calories in virtually every diet worldwide.
The advantages of “good” carbohydrates
Since all carbohydrates are broken down into sugars, why does it matter which carbohydrates you consume? Why is the carbohydrate in a teaspoon of sugar any better or worse than the equivalent amount of carbohydrate in lima beans, whole-wheat bread, or, for that matter, a chocolate bar? The simple answer is that different types of carbohydrates have different effects in the body.
There are two general types of carbohydrates:
• Simple carbohydrates are sugars—for example, glucose and fructose from fruits and some vegetables, and lactose from milk. But most of the sugar we eat is added to foods and beverages in the form of sucrose (from cane or beet sugar) and high-fructose corn syrup. Simple carbohydrates can cause spikes in blood sugar since they are digested and absorbed into the blood quickly.
• Complex carbohydrates, also called starches, consist of chains of two or more sugar molecules. Starches are the storage form of energy in plants. They are transformed by the body into sugar (mostly glucose), the body’s basic fuel. Foods rich in complex carbohydrates include grains and grain products (such as bread and pasta), beans, potatoes and corn.
Though complex carbohydrates are generally digested more slowly than simple carbohydrates, depending on their structure and how they are processed, many break down as quickly and thus also can cause spikes in blood sugar. For example, the carbohydrates in beans and brown rice are broken down slowly, while those in refined grains, such as white bread, are digested quickly.The healthiest complex carbohydrates are those that are unprocessed and high in fiber.
The effect of various carbohydrates on blood sugar is ranked by the glycemic index (GI). Some experts have claimed that avoiding foods with a high GI (which are broken down more quickly) in favor of whole grains (which are digested more slowly and thus may have a more modest effect on blood sugar) can aid weight loss and help prevent diabetes and heart disease. But the results of studies have been mixed. In any case, simply following the guidelines of a healthy diet (eating more whole grains, beans, fruits and vegetables; increasing fiber; and cutting back on sugary and highly processed foods) makes for lower glycemic impact in general.
From a health perspective, it’s more important to recognize that many foods high in sugar supply “empty” calories—that is, they have plenty of calories but few, if any, nutrients. In contrast, foods rich in both complex carbohydrates and fiber bring nutritional extras with them.
However, you need to be selective. White bread made from refined flour contains complex carbohydrates, for instance, but whole grains (such as oats, whole wheat and brown rice) are more nutritious, since they retain the bran and the germ, which are rich in vitamins, minerals, fiber and beneficial phytochemicals.
Getting the right carbs
Carbohydrates should supply the lion’s share (40 to 65 percent) of your daily calories. But choose them wisely. Eat plenty of high-fiber carbohydrate-rich foods: whole grains, vegetables, fruits and beans. These are the “good” carbohydrates—nutritious, filling and relatively low in calories. And fiber slows the absorption of the carbohydrates, so there’s less effect on blood sugar.
At the same time, limit your intake of sugary foods and beverages, refined- grain products (such as white bread) and salty snack foods. Many sugary foods are also high in fat, so they’re calorie-dense.
An easy way to get the right proportion of carbs is to fill half your plate with vegetables and fruit and a quarter with grains (preferably whole grains).
Keep in mind that most high-carb foods are not so high in calories in and of themselves. It’s what they’re often topped with (meat or cream sauces, butter and cheese on pasta, for example) that can double or triple the calories. Potatoes can be a problem because most are eaten as high-calorie fries or chips. There’s nothing wrong with small amounts of foods and beverages high in added sugar. But many Americans eat too much of them, adding lots of calories and leaving little room for more nutritious foods.