"Whole grains provide fiber, B vitamins, vitamin E, minerals, antioxidant phytonutrients and protein -- most of which are missing in refined grains," explains David W. Grotto, R.D., author of "101 Foods That Could Save Your Life" (Bantam Books, 2008). And they also help fill you up - and keep you satisfied -- for much longer than the refined sort. "They are complex carbohydrates that give you sustained energy, and since fiber takes longer to digest, they aren't absorbed into your system so quickly," he says.

The benefits go on
Eating a diet rich in whole grains does your body good in myriad ways. Studies have shown that the fiber and other nutrients provided by whole grains can help reduce blood pressure, heart disease and the risk of stroke. "The antioxidants contained in grains may also reduce risk of some cancers," says Tara Gidus, R.D., a nutritionist based in Orlando, Florida.

As an additional benefit, the complex carbohydrate energy your body gets from eating whole grains helps regulate levels of blood sugar. Unlike refined carbohydrates (like those found in white flour), which can cause a quick rise and then drop in blood sugar, whole grains are turned into glucose slowly and can help prevent unhealthy swings in blood-sugar levels. In fact, studies have shown that a diet high in whole-grain fiber can significantly reduce the risk of type 2 diabetes.

Whole grains and weight management
When you're trying to lose weight -- or maintain the healthy weight you're at -- whole grains can play a starring role. "Many people looking to cut calories try to eliminate all carbohydrates, but the truth is that whole-grain carbohydrates can actually help you achieve your weight-loss goals," says Grotto.

These complex carbohydrates are one of the best things you can eat when you want to feel full longer. Studies have shown that oats have the highest satiety factor of all the whole grains -- which is why a bowl of oatmeal or other cereal rich in oats is an ideal breakfast choice for anyone looking to lose weight.

The fiber -- both soluble and insoluble -- found in whole grains is the main reason why foods like whole-wheat bread, brown rice, quinoa and oatmeal are great diet choices. "Refined carbs provide empty calories and can actually have the effect of making you hungrier," says Gidus. "But the fiber in whole grains gives you lasting fullness, and helps control the dips in blood sugar that can leave you feeling unsatisfied soon after eating."

Smart substitutions
As you plan each meal or snack, look at the carbohydrate component and see if you can substitute a whole grain for a refined one. In other words, swap out white carbohydrates for brown ones like whole-wheat breads, crackers and pastas, brown rice, and whole-grain breakfast cereals. But don't limit yourself to the most common grains. Nutritious grains like quinoa, bulgur, buckwheat, barley, millet and emmer are delicious, easy to prepare and can be mixed into salads, hot cereals, soups, stews and rice dishes.

And don't worry if you still sneak some refined carbohydrates into your diet. "Try to get at least half of your grains to be whole grains each day," says Gidus. "And if you get more, that's even better."