They help digestion
Whole grains have other digestive benefits as well. The fiber content keeps bowel movements regular (studies have shown that people who eat more fiber need fewer laxatives). And they help ward off diverticulosis, the condition in which little pouches form in the colon wall, causing inflammation, constipation, diarrhea, and pain. Fiber is responsible for much of the benefit, but whole grains also contain lactic acid, which promotes "good bacteria" in the large intestine. These organisms aid digestion, promote better nutrition absorption, and may even beef up the body's immune system.
They can help lower cholesterol
Whole grains not only help prevent your body from absorbing "bad" cholesterol, they may also lower triglycerides, both of which are major contributors to heart disease. In fact, whole grains lower the risk of heart disease overall. One study found that women who ate 2-3 servings of whole grain products daily were 30% less likely to have a heart attack or die from heart disease compared with women who ate less than one serving a week. "Any form of whole grain—including whole wheat, oats, brown rice, barley, corn, quinoa, rye, buckwheat, and millet—will confer benefits for heart health," says Cheung. "When it comes to oatmeal, steel-cut is better than instant."
They lower blood pressure
The heart benefits of whole grains don't stop with cholesterol and triglycerides. They also lower blood pressure, one of the most important risk factors for heart disease. One study found a 19% lower risk of hypertension among men who ate more than 7 servings of whole grain breakfast cereal a week compared with those who ate one or less. A study of women also found a benefit. "Eating whole grains instead of refined grains substantially lowers blood cholesterol...triglycerides, blood pressure, and insulin levels," says Cheung. "Any of these changes would be expected to reduce the risk of heart disease."
They can help control weight
People who eat a lot of whole grains are more likely to keep their weight in check and less likely to gain weight over time than those who eat refined grains. In one study, women who consumed the most wheat germ, brown rice, dark bread, popcorn, and other whole grains had a 49% lower risk of "major weight gain" over time compared with women who favored doughnuts and white bread. Over the span of 12 years, middle-aged men and women who ate a diet high in fiber gained 3.35 pounds less than those with who went for refined products.
They redistribute fat
Even if eating whole grains doesn't actually make you lose weight, studies have shown that it can help you cut down on the amount of body fat you have and lead to a healthier distribution of that fat. Specifically, eating whole grains can leave you with less belly fat—what scientists kindly call "central adiposity"—which increases your risk of diabetes and other health woes.
They make you feel full
One way whole grains may help you control your weight is by making you feel fuller than refined grains such as cookies or white bread. "Whole grains take longer to digest and have a more satiating effect," says Gans, who is also author of The Small Change Diet. This could also help keep your portions under control. Try rye or protein-packed quinoa to get maximum fullness.
They help regulate blood sugar
One of the main benefits of whole grains is that compared to refined grains, they help keep your blood glucose from spiking, which can reduce your risk of type 2 diabetes, among other things. Women in one study who ate 2-3 servings of whole grains a day had a 30% lower risk of diabetes than women who ate little or no whole grain products. One analysis found a 32% lower risk of diabetes in people who ate 3 or more servings a day of whole grains versus a 5% risk reduction in those who ate refined grains. Something as simple as swapping one third of a serving of cooked white rice a day (about 2 ounces) for brown rice was associated with a 16% decline in type 2 diabetes risk. "Eating whole grains has been proven to have a protective effect against type 2 diabetes, so they are a smart choice for people with pre-diabetes or high risk of diabetes," says Cheung.