Eating whole grain products instead of refined ones saves you a hundred kilocalories a day
You'll find it easier to maintain your weight and lose weight if you eat whole grain products rather than their refined counterparts. So eat whole grain bread and pasta instead of white bread and pasta, and brown rice instead of white rice. According to a soon-to-be published study by researchers at the US Department of Agriculture, doing this can make a difference of nearly one hundred kilocalories a day.
The researchers gave a group of 40 adults a diet containing whole grain products - whole grain bread, cereals and pasta - for a period of six weeks. An equal-sized group of participants were given refined grain products. The researchers made sure that both groups consumed the same amount of kilocalories, carbohydrates, proteins and fats.
At the end of the six weeks the researchers found no statistically significant different effects of the whole grain - or the refined grain - diet on the participants' body composition. What the researchers did discover was that the whole grain diet boosted calorie burning, and the refined grain diet reduced calorie burning. The difference was 96 kilocalories per day.
This was partly because the whole grain group lost more kilocalories through their faeces [Fiber adjusted stool energy]. The other almost equally important reason was that the whole grain group burned more kilocalories when resting - so they had a higher resting metabolic rate [RMR].
At the beginning and end of the six-week experimental period the researchers gave the participants a portion of glucose and then determined how quickly the participants eliminated the glucose. The participants in the whole grain group did this more efficiently than the people in the other group, as the figure above shows.
The researchers suspect that consuming whole grains delays the uptake of carbohydrates and that the body therefore needs more time to transport the carbohydrates to the places where they are needed. That would explain the higher resting metabolic rate.
Wild speculation on our side
You may wonder whether this is the whole story. The whole grain group had 5-6 times more alkylresorcinols [basal structure shown above right] in their blood than the other group did. The researchers regard these substances as markers for the consumption of whole grains and nothing more.
The alkylresorcinols shown above here are found in whole grains, but similar compounds are also found in cashew nuts. And these compounds just happen to boost metabolism and calorie burning... Get the idea where this is leading...?
"These findings provide new evidence of energetic benefits and improved oral glucose tolerance when whole grains replace refined grains in the diet," the researchers conclude. "These findings strengthen the support for basing dietary guidance pertaining to whole-grain consumption on favorable effects relating to the regulation of the energy balance."
The researchers were funded by the government and the cereals manufacturer General Mills.
Am J Clin Nutr doi: 10.3945/ajcn.116.139683.
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