New Study Suggests Calories May Not Count

CAMBRIDGE, Mass., Oct. 14 /PRNewswire/ -- One of the most controversial aspects of low-carbohydrate diets such as the Atkins Nutritional Approach™ is their rejection of the tyranny of calorie counting. Critics of these plans claim that the reason people lose weight on low-carb diets is the same reason they lose weight on any other diet: they actually consume fewer calories, presumably because they are bored with monotony of all that steak. Now, a new study by Harvard researchers suggests that these critics are wrong and that people lose at least as much weight on a low-carbohydrate diet than those on a low-fat diet, even when they consume significantly more calories every day.

Last May two studies were published in the New England Journal of Medicine that showed the benefits of low-carbohydrate diets, but they left some open questions. "Some people have argued that if there is a difference between low- fat and low-carb diets as some studies have shown, it's due to caloric restriction because people are either bored and thus eat less or people are satiated and thus eat less," says Penelope Greene, a nutritionist at the Harvard School for Public Health and chief author of the new study. "My own view is that if it's boring then that's a particular concern, because that's not a diet that can be maintained. If it's caloric restriction because it's satiating and people are happy, I'm not sure that that's necessarily a bad thing. That seems like a good thing."

To prove that something more than mere caloric restriction is the reason that low-carb diets work, Greene and her colleagues had to improve on the previous "free-feeding" studies. In these experiments, subjects were randomly divided into two groups, and told to follow either a low-fat or a low-carb diet on their own. The researchers did not know how much the subjects actually consumed, which meant that it was possible that the low-carb eaters were leaving food uneaten on their plates. Greene and her colleagues, Walter Willett, Juniper Devicis and Antoine Skaf set out to perform a more carefully controlled, controlled-feeding experiment in which the subjects would be given prepared meals with portions weighed to the nearest gram.

Controlled-feeding experiments are notoriously difficult, Greene explains. "A lot of people didn't think we could do this," she says. After running the pilot study, which consisted of 21 subjects, she understands why. For several months she was putting in 10- to 15-hour days, seven days a week, supervising food preparation, color coding meals, and keeping records. The researchers contracted out the preparation of the food to an upscale Italian restaurant in Cambridge, MA, Ristorante Marino. "They were very used to doing catering," she says, "but not in weighing food to the nearest gram." Furthermore, they had to produce two different preparations of most foods -- low-fat and low-carb -- at five different calorie levels.

The pilot study, which was performed last fall, consisted of three sets of seven subjects each. "This was a very motivated group," Greene explains. "They were all over-fifty, overweight and overly scared. We had hundreds of people who wanted to enroll." The subjects would pick up their meals every evening and return the uneaten portion from the previous day. "There was very, very little of that," Greene says. "What I got back were little dregs of lettuce, literally."

The first group was fed a low-fat diet, consisting of 1,500 calories a day for women and 1,800 calories a day for men. The second group was given a low-carbohydrate diet, but the same number of calories. To test the hypothesis that the weight loss is not due to caloric restriction, the third group was also fed a low-carb diet, but 1,800 calories a day for women and 2,100 calories a day for men. Over the 12-week course of the study this group consumed 25,000 extra calories. According to many diet books, 3,500 calories equals one pound, which means that the third group should have lost 7 pounds less than the other two groups. In fact, to within statistical error the subjects in all three groups lost more or less the same weight. "I think this was the most surprising thing, and made this very much worth doing," Greene said. "Keep in mind that there are people who would have argued that the second group should have not done as well because of all the fat they ate."

Greene is quick to point out that this was only a pilot study, though "probably the most elaborate pilot study I have ever heard of. The purpose of the experiment was to see if under these controlled conditions there was really anything to warrant a larger study. And the answer is yes, certainly."

Source: Yahoo