FRIDAY, April 18, 2003 (HealthDayNews) -- Obese women who are otherwise healthy can lose twice the weight on a low-carbohydrate diet plan as on a traditional low-fat plan.
And they can do so without compromising their cardiovascular health, at least in the short term, new research concludes.
The new report, published in the April issue of The Journal of Clinical Endocrinology and Metabolism, promises to refuel the diet debate over whether low-carb or low-fat is the better approach.
The controversial low-carbohydrate approach to weight loss was popularized by Dr. Robert Atkins, who died Thursday from injuries sustained in a fall during a recent snowstorm.
Because low-carbohydrate plans include a high percentage of calories from fat and protein, concern has been expressed over the potential cardiovascular damage such a diet might do.
Study author Bonnie Brehm, an assistant professor in the college of nursing at the University of Cincinnati, says the results surprised her: "We had hypothesized that this [low-carb plan] would harm their cardiovascular health."
"This was funded by the American Heart Association [as well as other sources]. Our hypothesis was that the low-fat group would lose more weight and body fat for sure."
In fact, after six months, the 22 women on the low-carb plan averaged an 18.7-pound loss, while the 20 women on the low-fat plan averaged an 8.5-pound loss.
Both groups also showed improvement in markers of cardiovascular health, such as blood pressure, blood lipids and blood cholesterol levels, Brehm says. The women ranged in age from 29 to 58, but most were in their 40s. Their body mass index (BMI) ranged from 29.5 to more than 37. A BMI of 30 marks the beginning of obesity.
The low-carbohydrate group, at the three-month mark, was averaging 15 percent of calories from carbohydrates, 28 percent from protein and 57 percent from fat. At the six-month mark, they were eating 30 percent carbs, 23 percent protein and 46 percent fat.
The low-fat group was averaging 54 percent of calories from carbohydrates three months into the study, 18 percent from protein and 28 percent from fat. At six months, the totals were 53 percent carbs, 18 percent protein and 29 percent fat.
Average calorie intake was similar for both groups -- 1,302 a day for the low-carb group after six months and 1,247 for the low-fat group.
Under current recommended guidelines set by the National Academies of Sciences, Americans are advised to take in 45 percent to 65 percent of calories from carbohydrates, 20 percent to 35 percent from fat and 10 percent to 35 percent from protein.
Brehm isn't sure why the low-carb group lost more weight. The women agreed they would not change their exercise habits during the study.
"I told them, if you are a couch potato today [at the start of the study], you must remain a couch potato for six months," Brehm says. "If you walk four times a week, continue."
She plans to research the matter further.
Another dietary expert familiar with the new study says she wouldn't advise women to go the low-carbohydrate route to lose weight.
"The study was only six months," says Evelyn Tribole, a dietitian and author of numerous nutrition books, including the revised "Intuitive Eating," due out from St. Martin's Press later this year.
She points out the pitfalls of low-carbohydrate diets.
"When you go on such a low-carb diet, there's not much food left to select from," she says. And exercising for an hour or 90 minutes at a stretch may be more difficult on such a diet, she says, because the body depends on carbohydrates for energy.
More information
For the updated National Academies of Sciences' report on recommended intake of proteins, carbohydrates and fat, click here. The U.S. Department of Agriculture offers these dietary guidelines.
