Weighing in on Whole Grains: A Review of Evidence Linking Whole Grains to Body Weight1

Currently, an estimated 32.9% of American adults are overweight, 34.3% are obese, and 5.9% are extremely obese (38). In fact, adults defined as being normal weight, i.e., those whose body mass index (BMI) falls in the range of 18.5 to 24.9 kg/m2, are a minority within the U.S. population. Coupled with declines in physical activity, overconsumption of calorie-rich, nutrient-poor foods is contributing to this obesity epidemic. Recent estimates indicate that 90% of the U.S. population is exceeding its discretionary calorie allowance and not meeting recommendations for most dietary nutrients (25). One group of problematic foods that is high in sugar and fat and contributes to excess consumption of discretionary calories is refined grain-based foods, including many desserts and snack foods. A modest weight loss of roughly 5–10% of body weight can translate into substantial health improvements in metabolically at-risk individuals (2,49,50,56). For instance, in a study of overweight and obese adults with impaired glucose tolerance, a 6% weight loss achieved through lifestyle modification translated into a 58% reduction in the incidence of type 2 diabetes (23). Although many lifestyle and dietary modifications have been shown to prevent weight gain or promote successful weight loss, another effective strategy may be the substitution of whole-grain equivalents for refined-grain foods (38). On January 31, 2011, the Dietary Guidelines for Americans 2010 (DGA) was released. With respect to grains, the 2010 DGA recommends that individuals “consume at least half of all grains as whole grains” and “increase whole-grain intake by replacing refined grains with whole grains.” For an adult consuming 2,000 kcal daily, this translates into consumption of at least three ounce-equivalent servings per day of whole grains (51). Based on a systematic review of the evidence, the DGA advisory committee concluded that “moderate evidence shows that intake of whole grains and grain fiber is associated with lower body weight.” Weighing in on Whole Grains: A Review of Evidence Linking Whole Grains to Body Weight1