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Bad News for Rice Cakes |
A low glycemic diet, rich in the type of carbohydrates that maintain a more stable blood sugar beats out a conventional low fat diet in reducing the risk factors for heart disease and diabetes, according to a new study.
Researchers compared a diet rich in carbohydrates with a low glycemic index -- the type that stabilizes blood sugar -- with a conventional low fat diet that included carbohydrates with a high glycemic index.
"Carbohydrates with a low glycemic index are absorbed through the small intestine and converted to blood sugar at a much slower rate than high glycemic, resulting in a more stable blood sugar and much less insulin being produced," said Mark A. Pereira, a University of Minnesota epidemiologist. "So that would help prevent or control diabetes."
The work by Pereira and his team appears in the Nov. 24 issue of the Journal of the American Medical Association.
In the study, those on the low glycemic diets also achieved better improvement in blood pressure and blood fats, and their resting metabolic rate -- the rate at which the body burns energy or calories at rest -- didn't drop as much as it did for those on the low fat diet.
Low glycemic menus within the studies normally allowed more fat -- about 30 percent -- than the low fat, which allowed 18 percent fat
Pereira and his colleagues assigned 39 overweight or obese young adults, ages 18 to 40, to either the low glycemic diet or the low fat diet. The low glycemic diet got 43 percent of calories from carbohydrates, 27 percent from protein, and 30 percent from fat, Pereira said.
(For the sake of comparison, the popular Zone Diet consists of 40 percent of calories from carbohydrates, 30 percent from protein, and 30 percent from fat. Low glycemic carbohydrates are recommended.)
Those on the low fat diet got 65 percent of their calories from carbohydrates, 17 percent from protein, and 18 percent from fat. Both diets were restricted in calories to achieve a 10 percent weight loss.
Food was provided for the subjects. The low glycemic menus featured such foods as steel-cut oatmeal, barley and whole-grain breads. The menus for the low fat diet included carbohydrate foods with a higher glycemic index, such as instant oatmeal, white bread and white rice.
A decrease in blood fats and blood pressure and insulin resistance twice as great for the low glycemic group over the low fat group
Pereira's team measured blood pressure, insulin resistance (a predictor of diabetes), blood fats and other risk factors for diabetes and heart disease, before and after the weight loss. "Generally, what we found across the board for blood fats and blood pressure and insulin resistance is, the decrease with weight loss was twice as great for the low glycemic group compared to the low fat group."
Both groups averaged the same amount of weight loss, the 10 percent goal, but the dieters on the low glycemic diet reported less hunger. And their resting metabolic rate, which typically drops during weight loss, dropped less in the low glycemic eaters.
"For the conventional low fat dieters, the metabolic rate slowed down by 175 calories a day," Pereira said. "For the low glycemic group, there was a 95-calorie drop."
The new study echoes those of previous studies, Pereira added.
Help for those on a low glycemic diet