If we needed more reason to switch from refined grains to whole grains, a new study shows that people who eat more healthy whole grains have smaller stores of visceral abdominal fat (VAT), a.k.a. belly fat. Large stores of VAT are thought to be dangerous since they are linked to metabolic syndrome, which increases the risk for heart disease and type 2 diabetes. According to the study, one-third of Americans are considered obese.
Whole grains are those that still possess the healthy outer layers — the bran, endosperm, and germ. When grains get processed or refined, they lose these parts, which are high in vitamins, minerals, and fiber.
People who ate more than three servings of whole grains per day had, on average, 10% less belly fat than people who ate one or fewer servings of whole grains per day — unless they ate a lot more refined grains as well.
The new study looked at over 2,800 participants of all ages from the famed Framingham Heart Study, and assessed just how much of their diets consisted of whole grains and how much was made up of refined grains. Study author Nicola McKeown explains that "[f]or example, a slice of 100 percent whole wheat bread or a half cup of oatmeal constituted one serving of whole grains, and a slice of white bread or a half cup of white rice represented a serving of refined grains." Participants’ waists were measured and their bodies scanned to determine how much belly fat they were carrying.
The results held true even after correcting for other variables like fruit and vegetable intake, fat intake, alcohol consumption and smoking. This suggests that it is indeed the whole grains themselves that have the effect, rather than a mix of other dietary factors.
According to the study, "greater education is needed for the public to understand clearly the term whole grain, what constitutes a serving, and the health benefits associated with substituting refined — grain with whole-grain foods." So don’t just have a few Triscuits™ along with your pizza — the key is substitution.
The study was published in the September 29, 2010 online issue of the American Journal of Clinical Nutrition. McKeown is a researcher at Tufts University.