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Study: Not all calories are created equal

(CBS News) Research shows only one out of six overweight people can maintain even 10 percent of any weight loss over the long term. Now a new study, published in the Journal of the American Medical Association, has found a possible explanation: all calories are not created equal.

After losing about 30 pounds weight, 21 young adult participants were put on three different diets to see how they affected metabolism: low fat, low carb and low glycemic index. While on the low fat diet, people burned fewer calories, making it harder to keep off weight. People on the low carb diet burned the most calories, but had increased risk of heart disease, while the low glycemic diet offered medium calorie burning, with little risk of negative effects. Researchers say diets that reduce a blood sugar surge after a meal, either low glycemic or low carb, may be preferable to low fat for those trying to achieve lasting weight loss.

The researcher who led the study, Dr. David Ludwig, of Boston's Children Hospital, explained on "CBS This Morning," "These findings suggest, from a metabolic perspective, all calories are not alike. And for the best long-term outcomes, avoid restricting any major nutrients, either fat or carbohydrate, and focus on reducing refined carbs like white bread, white rice, potato products and sugary foods."

He added, "Our findings suggest that actually trying to restrict either carbs or fat is not the best way (to achieve long-term weight loss) and instead to focus on the quality of the fats and the quality of the carbs."

Ludwig said, "The traditional carbohydrates that we've eaten for thousands of years, for example steel-cut oats rather than instant oats or stone-ground breads rather than highly-processed breads, these traditional carbohydrates digest slowly and they slowly raise blood sugar slowly, so there isn't the same surge and crash.

"But all of the refined carbs that invaded our diets with the low-fat craze seems to lead to metabolic changes not only making us hungrier, but causing metabolism to fall. And that combination is a recipe for weight gain."

For more on the study and how to make better food choices, watch Ludwig's full "CTM" interview in the video above.

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