Whole grains seem to both lower the number of calories your body absorbs during digestion and speed metabolism, explained study author J. Philip Karl. He’s a nutrition scientist who did the research while a Ph.D. student in nutrition at Tufts University in Boston.
While other studies have found that people who eat whole grains are slimmer and have lower body fat than those who do not, Karl said it has been hard to separate the effects of whole grains from regular exercise and a healthier diet overall.
So, for the new study, “we strictly controlled diet. We didn’t let them lose weight,” he said.
The researchers did that by pinpointing the specific caloric needs of each of the 81 men and women, aged 40 to 65, in the study.
For the first two weeks of the study, everyone ate the same types of food and the researchers computed their individual calorie needs to maintain their weights. After that, the researchers randomly assigned people to eat either a whole-grain or refined-grain diet.
The men and women were told to eat only the food provided and to continue their usual physical activity.
Those on the whole-grain diet absorbed fewer calories and had greater fecal output. Their resting metabolic rate (calories burned at rest) was also higher. The fiber content of whole-grain foods, about twice that of refined-grain foods, is believed to play a major role in those results, Karl said.
“The energy deficit in those eating whole grains compared to refined grains would be equivalent to the calories you would burn if you were to walk about a mile [in] about 20 or 30 minutes,” he said. But the study did not prove that whole grains cause weight loss.
”We don’t know over the long term if it would translate to weight loss,” Karl said, but his team suspects it would. “This would translate to about 5 pounds in a year,” Karl estimated.
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SOURCE: HealthDay News