People who consume several servings of whole grains daily while limiting their intake of refined grains have less of a dangerous type of body fat known as visceral adipose tissue than people with higher intakes of refined grains, researchers have found. Unlike subcutaneous fat, which sits just below the skin, visceral fat surrounds organs in the abdomen and is linked to the development of metabolic syndrome (a cluster of conditions such as high blood pressure and insulin resistance) and to an increased risk of cardiovascular disease and Type 2 diabetes.
To determine how the consumption of whole and refined grains affects the distribution of subcutaneous and visceral fat, researchers looked at diet questionnaires from 2,800 men and women ages 32 to 83 who were participants in the Framingham Heart Offspring and Third Generation study. In addition, they examined the results of multidetector-computed tomography scans of the participants, which allowed them to determine each person’s level of visceral and subcutaneous fat.
The data showed that levels of visceral fat were roughly 10% lower in people who had reported eating three or more servings of whole grains a day while limiting their daily consumption of refined grains to one serving. The association remained after the researchers adjusted for other lifestyle factors, including smoking, alcohol intake, fruit and vegetable intake, percentage of calories consumed from fat, and physical activity. Participants who ate three daily servings of whole grains but who did not limit their consumption of refined grains did not have lower levels of visceral fat.
According to lead study author Nicola McKeown, PhD, “Whole grain consumption did not appear to improve [visceral fat] volume if refined grain intake exceeded four or more servings per day.” This finding highlights the importance of substituting refined grains in the diet with whole grains, rather than just adding whole grains. “For example, choosing to cook with brown rice instead of white or making a sandwich with whole grain bread instead of white bread,” explains McKeown.
The researchers note that their study was observational, and therefore does not show cause and effect, and it involved relatively small numbers of people. However, they suggest that the apparent link between grain consumption and body fat distribution warrants further investigation in larger studies to determine what causes the association.
To learn more about the research, see the article “Less Refined, More Whole Grains Linked to Lower Body Fat” or see the study’s abstract in the American Journal of Clinical Nutrition. And for more information about incorporating whole grains into your diet, check out the article “Going With the Whole Grain.”