We hear in the media and from government and academic institutions we should consume whole grains for health and weight-management. But with specific reference to weight-management are the whole-grains commonly purchased of any benefit?
First, what is a whole-grain? A whole-grain is one where the intact kernel (containing the endosperm, germ, and bran) contains the same relative proportions as they exist in the unprocessed kernel.
The most commonly consumed whole grains worldwide are wheat, brown and long-grain rice, maize, oats, barley, rye, millet, sorghum, and triticale. Currently these grains are more commonly processed (e.g., milled, cracked, rolled, ground, crushed, and flaked) and reconstituted before consumption than consumed in their intact form.
When a grain is refined the texture and stability improves, however, much of the nutritive value is lost. Whole grains are richer in dietary fiber, vitamins, minerals, phytoestrogens, phenolic compounds, and phytic acid relative to their refined counterparts.
A clear distinction needs to be made between a true whole-grain and a food that contains whole grains. Most packaged foods on store shelves that promote their whole-grain goodness contain some level of whole-grain. This should not be confused with consuming a true whole-grain, only the whole-grain and nothing but the whole-grain. A product that contains some whole-grain rolled oats among other ingredients is not the same as purchasing just rolled oats. And your body knows the difference.
Recent clinical trials provide little evidence for any beneficial effect on weight with common “whole-grain” containing foods. Most likely this is because food manufacturers have stretched the legal definition of “whole grain” as far as they possibly can to make the label claim for whole grain but providing a processed food dense in calories and sparse in fiber, vitamins and other nutrients.
Whole grains are superior to refined grains (which lack the germ and bran) for overall health. So it’s still a smarter choice if you’re going to buy grain-based foods to choose those that clearly have as the first ingredient whole-grain or whole-wheat.
However, for the purposes of weight-management, there is no benefit when purchasing whole-grain-containing products compared to refined-grain products of similar class. If any benefit of whole-grain is going to be conferred to the buyer for weight-management purposes the product should be 100% whole-grain and not a food only containing 100% whole-grain. Quaker Oats (Ingredient: Rolled Oats), for example, qualifies as a 100% whole-grain food.
In conclusion, because cereal grains are always more calorie dense by weight than fibrous vegetables, those who are committed to weight-loss should meticulously weigh and measure grains consumed and, in my opinion, limit their intake to no more than 150 calories per day from foods containing grain (e.g. about 3/4 cup cooked rice or pasta, 1/2 cup dry oats, slice and a half of whole-grain bread).
Source: Adv Nutr vol. 3: 697-707, 2012
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