Jun 27, 2012 9:19 PM GMT
It's a small study but lends preliminary credence to Gary Taubes' Good calorie, bad calorie argument -
A new study is raising questions about the age-old belief that a calorie is a calorie.
The research finds that dieters who were trying to maintain their weight loss burned significantly more calories eating a low-carb diet than they did eating a low-fat diet.
But some experts say these findings are very preliminary.
The study, funded by the National Institutes of Health, was designed to see if changing the type of diet people consumed helped with weight maintenance because dieters often regain lost weight.
So scientists had 21 obese participants, ages 18 to 40, lose 10% to 15% of their initial body weight (about 30 pounds). After their weight had stabilized, each participant followed one of three different diets for four weeks. Participants were fed food that was prepared for them by diet experts. The dieters were admitted to the hospital four times for medical and metabolic testing.
Here’s a look at the three types of diets used in the new study:
A low-fat diet, which is about 20% of calories from fat, 60% from carbohydrates, 20% from protein. It emphasizes whole-grain products and fruits and vegetables and cuts way back on oils, nuts, fatty meats and other high-fat foods.
A low-carb diet, similar to the Atkins diet, with only 10% of calories from carbohydrates, 30% from protein, 60% from fat. This diet emphasizes beef, fish, chicken, eggs, cheese, some vegetables and fruits while slashing the consumption of breads, pasta, potatoes, rice, cakes, cookies and starchy vegetables.
A low-glycemic index diet, similar to a Mediterranean diet, is made up of vegetables, fruit, beans, healthy fats (olive oil, nuts) and mostly healthy grains (old-fashioned oats, brown rice). It gets about 40% of daily calories from carbohydrates, 40% from fat and 20% from protein.
Source: Journal of the American Medical Association
The diets had the same number of calories, but the fat, protein and carbohydrate content varied. Those diets:
•A low-fat diet which was about 20% of calories from fat and emphasized whole-grain products and fruits and vegetables.
•A low-carb diet, similar to the Atkins diet, with only 10% of calories from carbohydrates. It emphasized fish, chicken, beef, eggs, cheese, some vegetables and fruits while eliminating foods such as breads, pasta, potatoes and starchy vegetables.
•A low-glycemic index diet, similar to a Mediterranean diet, made up of vegetables, fruit, beans, healthy fats (olive oil, nuts) and mostly healthy grains (old-fashioned oats, brown rice). These foods digest more slowly, helping to keep blood sugar and hormones stable after the meal.
Findings, published in this week's Journal of the American Medical Association: Participants burned about 300 calories more a day on a low-carb diet than they did on a low-fat diet. "That's the amount you'd burn off in an hour of moderate intensity physical activity without lifting a finger," says senior author David Ludwig, director of the New Balance Foundation Obesity Prevention Center at Boston Children's Hospital.
"Participants burned 150 calories more on the low-glycemic index diet than the low-fat diet. That's about an hour of light physical activity," he says.