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MONDAY, Jan. 26 (HealthDayNews) -- Carbohydrates may not be the real villains in the hard-fought battle against the bulge after all.

A small group of older men and women actually lost weight on a complex carbohydrate diet that let them eat until they were full without counting calories.

"This runs counter to the current cult of carbohydrate aversion," says William J. Evans, senior author of the National Institute on Aging-funded study that appears in the Jan. 26 issue of the Archives of Internal Medicine.

Losing weight, of course, has become the great American pastime -- and with good reason.

"If someone is overweight with a BMI [body mass index] of 25 or greater, they are at risk for more disease including cancer, heart disease and diabetes," says Samantha Heller, senior clinical nutritionist at New York University Medical Center in New York City. "Even losing a few pounds can help lower blood pressure and help regulate and manage cholesterol levels."

There has been some evidence that low-fat, complex carbohydrate (think whole grains) diets coax the pounds off. But it wasn't clear if they might work because overall food consumption was lower or what the metabolic effects of less fat were.

For the new study, 34 people aged 55 to 80 with impaired glucose tolerance (a risk factor for type 2 diabetes) were randomly assigned to one of three 12-week programs. The control program was a "typical American diet" of 41 percent fat, 14 percent protein and 45 percent carbohydrates. The remaining individuals followed a low-fat, high-carbohydrate diet (18 percent fat, 19 percent protein, 63 percent carbohydrate) either with or without aerobic exercise.

Participants, who were not told this was a weight-loss study, came to the University of Arkansas' nutrition, metabolism and exercise laboratory center in the morning for breakfast. The rest of their food for the day was then provided to them.

"We gave all of our subjects half again as much food as we felt they needed to maintain their weight, 150 percent of their energy requirements," says Evans, who is a professor in the Donald W. Reynolds Department of Geriatrics at the University of Arkansas for Medical Sciences College of Medicine. They were told they could eat as much as they wanted. Any food that was uneaten was brought back and weighed.

Breakfast in the diet group consisted of cereal or oatmeal. Snacks consisted of lemon pudding, popcorn and crispbread crackers.

Participants in the low-fat, high-carb groups lost weight and those who exercised lost even more. The average weight loss was almost 11 pounds.

These differences were seen despite the fact that all participants had the same calorie intake. "We were able to demonstrate that subjects could experience weight loss with no decrease in calorie intake, only a decrease in fat intake," Evans says.

Metabolic rates were the same for all participants as well.

"There is really very little evidence that humans actually turn carbohydrate into fat," Evans explains. "How much fat we have is by and large the product of over- or under-eating fat or increasing the burning of fat as fuel."

Why is it, then, that the protein-focused Atkins diet also produces weight loss?

"What happens when you reduce carbohydrate intake is that your appetite is greatly suppressed. So as long as your carbohydrate intake is extremely low, you're not as hungry, and you end up eating fewer calories and losing weight," Evans says.

"The big problem with Atkins is once you decide that you've lost enough weight and want to eat bagels and bread and pasta again, suddenly you're hungry again and start eating a lot more food. The rate of recidivism of Atkins is extraordinarily high," he adds.

While Evans' study focused on complex carbohydrates such as whole grains, his current research is finding similar results with simple carbohydrates such as white bread and pasta. "In my opinion, it's the low fat rather than the type of carbohydrate," Evans says. But that study is not yet completed.

It's also important to note the just-published study was very small, with only 11 or 12 people in each group. "It needs to be repeated with bigger groups and more specific measurement of food intake," Heller says. "It's not conclusive."

More information

For more on proper nutrition, visit the U.S. Agriculture Department. The American Diabetes Association has more on type 2 diabetes.

(SOURCES: William J. Evans, Ph.D., professor, Donald W. Reynolds Department of Geriatrics, University of Arkansas for Medical Sciences College of Medicine, Little Rock; Samantha Heller, M.S., R.D., senior clinical nutritionist, New York University Medical Center, New York City; Jan. 26, 2004, Archives of Internal Medicine)

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