Don’t blame grains
But what about grains? If grain consumption was a cause of obesity, as Wheat Belly author Dr. William Davis asserts, then there should be pretty good evidence to support that claim. There is not.
Several major scientific review articles published in the past five years have shown that consumption of whole grains exerts positive effects on body weight and health. These results come as no surprise to me because they confirmed what I have known for years from staying current on the literature in this area.
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In a literature review I wrote for the October 2007 issue of Journal of the American Dietetic Association (now published as the Journal of the Academy of Nutrition and Dietetics), nine separate studies that included diet information on more than 160,000 men and women all found inverse relationships between whole grain intake and body mass index. In other words, men and women who consumed more servings of whole grains per day were slimmer than their counterparts who consumed the fewest servings of whole grains per day.
Aside from a few grain-bashing outliers, the vast majority of health professionals are in agreement on whole grains and would urge patients to consume more of them.
But what about refined grains? Americans definitely consume more refined grains than whole grains, and we have repeatedly been reminded to cut back on them. But are they really as bad as they have been portrayed? Are they a cause of obesity and other health problems? The evidence may surprise you.
Take body weight, for example. Far from being associated with poorer weight control, refined grain intake has very little relationship to body weight or obesity risk. Most large epidemiological studies reveal rather small differences in body weight between those who consume high or low amounts of refined grains.
In one study of nearly 35,000 women, published in 1998 in the American Journal of Clinical Nutrition, those who consumed 30 servings per week of refined grains weighed only about one pound more than women who consumed only four servings per week of refined grains.
In a study of more than 42,000 male health professionals, also published in the American Journal of Clinical Nutrition, in 2002, there was zero difference in body weights of men who consumed approximately 30 servings of refined grains per week compared to men who consumed fewer than five servings of refined grains per week. These findings are very similar to those of other studies, and show that body weights of men and women are very similar despite a 6- to 7.5-fold difference in refined grain consumption.
Even when you dig deeper and focus not on body weight itself but on specific body fat depots that pose greater health risks, grain consumption comes out just fine. A 2010 report from the Framingham Heart Study found that the lowest levels of harmful visceral abdominal fat were observed in participants who consumed approximately two servings per day of refined grains and two servings per day of whole grains, a combination consistent with the Dietary Guidelines for Americans.
