Starches and sugars are your body's main source of energy. You need them to fuel your muscles. In fact, your brain needs 130 grams of carbs a day just to function properly! A carbohydrate-free diet, or a diet that’s too low in carbs, can be both dangerous and too low in nutrients.

If you're on a high-protein diet, you still need carbohydrates. The good ones.

Some carbohydrates support your health while others drag it down. Too many of the bad carbohydrates raise your triglycerides and make your blood thicker, putting you at risk for heart disease. They also contribute to carbohydrate cravings and diabetes. The trick is to eat enough good carbs and very few bad ones. It's a balancing act, but not too difficult once you understand the concept. So just which carbs are good and which are bad? And why?

Good carbs are whole foods from plants that contain both sugars and fiber. They include beans, whole grains, starchy vegetables, and fresh fruit. Substitute some of them for saturated (animal) fats and they can help lower your cholesterol. Their fiber binds to cholesterol, carrying it out of your body, and also keeps your blood sugar level.

Bad carbs are processed starches and sugars. They include sugar, honey, and refined grains like white flour and white rice. They are absorbed quickly and can trigger an insulin response, causing your blood sugar to drop suddenly.

Insulin resistance
When you eat any carbohydrate — either a sugar or a starch — your pancreas releases insulin to help your body utilize it. When you eat large quantities of carbohydrates, especially those that are refined and low in fiber, you run the risk of releasing too much insulin. Some of this excess insulin remains in your blood and causes high blood sugar. High blood sugar is another term for diabetes. When you make too much insulin too often, it can lead to diabetes.

Over time, your body may stop using insulin properly. This is called insulin resistance. It not only leads to diabetes, but heart disease, obesity, hypertension, and blood clots as well.

Good carbs, on the other hand, are higher in fiber and are digested slowly. They rarely lead to insulin resistance when you eat them in moderation. In fact, they tend to stabilize your blood sugar.

The health food industry is pushing bad carbs
Health food stores are filling up their shelves with junk foods. I'm disheartened with the amount of foods they’re selling that contain bad carbs.

Here are a few to watch out for and avoid as much as possible:

• White rice. You may find organic white basmati rice in health food stores and think it’s good for you. It's not. White rice has been stripped of its nutritious hull that contains B vitamins and magnesium. Eat it along with vegetables and protein and it isn’t so bad. But I don’t consider any white rice a "good carb." It's low in nutrients and turns to sugar too quickly.
• Unenriched or enriched wheat flour. This is white flour, plain and simple. "Unenriched" wheat flour means the food contains white flour stripped of nutrients with none put back. Enriched flour is no better. Neither the fiber nor much of the nutrients that were removed is replaced. You may find white flour in organic breads, crackers, and cookies, but "organic" doesn’t necessarily mean "nutritious." Treat refined flour like white rice – it's acceptable in very small quantities, but has little nutritive value.
• Spinach and tomato pastas. Just because they look dark doesn't mean they’re unrefined. Most spinach and tomato pastas are made from white flour dyed a darker color from the added vegetables. Vegetable juices just make white pasta look healthier than it is.
• Pure cane sugar juice. I know a lot of it is organic and that's great for the environment. But pure cane sugar juice acts the same as plain old sugar. It contains a minimal amount of nutrients, feeds Candida (intestinal yeast) and cancer cells, and causes insulin to spike just like white sugar.

  Five years ago, a nutritionally minded doctor put out a line of instant cereals. I noticed that they contained organic pure cane sugar juice. "What's the difference between this sweetener and refined sugar?" I asked him. "Nothing," he answered. "I use it because people like the way it tastes." I appreciated his honesty, but not his decision.

• Fructose and high fructose corn syrup. These don’t raise blood sugar levels very much, but they raise total cholesterol levels and harmful LDL cholesterol. Worst of all, they contribute to a sluggish immune system. Fructose may be the single substance that’s causing an increase in diabetes. It’s found in soft drinks and many fruit drinks. Fructose is also an ingredient in many "health food" cookies and cakes.
• Honey and maple syrup. These sweeteners trigger an insulin response, contribute to inflammation, and can lower your immunity. Just because they're natural doesn’t mean they're healthy. If you want a safe sweetener without any calories that won’t affect insulin levels, stick to stevia, a powder made from the leaves of the stevia plant. You can find it in health food stores.

Net carbs: Pushing confusion to the limit
Read all product labels carefully. Some are very misleading. A growing number of snack foods now contain carbohydrates made from sugar alcohols called "net carbs." This makes foods sound healthier and lower in calories than they are. Companies are saying these sugars "don't count." They do!

These sugar alcohols contain the same amount of calories as other sugars. If you’re trying to control your weight, all carbs count!

If you limit your carbohydrates as part of a weight-loss program, "net carbs" is deceptive. Every gram of carbohydrate is four calories, whether a food company “counts” it or not. A low-carb energy bar with two "net carbs" does not have eight calories from carbohydrates. The 25 grams of total carbohydrates it contains, when sugar alcohols are included, means that 100 of its calories come from carbs. Count all the carbs and all the calories.

Eat more good carbs:
Get 90 percent of your carbohydrates from whole foods. Beans, brown rice, corn tortillas, polenta, and starchy vegetables are all good carbs. Eat small amounts of them along with protein and vegetables rather than one large carbohydrate meal.

Some good carbs, such as potatoes, have gotten a bad rap because they’re high on the glycemic index. This means they turn into sugar quickly. But Nancy Appleton, Ph.D., author of Kick the Sugar Habit, is furious about this.

"The glycemic index is a hoax," she told me. "If you eat any one of these foods alone that's high on the glycemic index, it will raise your blood glucose. But if you eat them with protein and fat, you won't. That’s the way we should eat!"

Don't be afraid or reluctant to eat some carbohydrates with your meals if they are unprocessed and are eaten with plenty of vegetables, protein, and a little fat. Just make them the good carbs, and keep your portions small.

Appleton, Nancy. Lick the Sugar Habit, Avery Publishing, 1996.

Haas, Elson. Staying Healthy With Nutrition, Celestial Arts, 1992.

Tallmadge, Katherine. "Do Net Carbs Add Up?" Washington Post, February 25, 2004.