NEW YORK, April 8 (UPI) -- A review of medical studies dating back to the 1960s has found no indications cutting carbohydrates from the diet is an effective way to lose weight, researchers reported Tuesday.
The researchers, led by Dr. Dena Bravata of Stanford University School of Medicine in Palo Alto, Calif., presented their findings at a special obesity news conference.
"I think there's a reason they're (low-carb diets) in vogue and that's because in the short-term they work," Bravata told United Press International. "And the reason they work is not because people are restricting their carbohydrates, it's because they're restricting calories."
Bravata added, "These diets are really popular. Are they good for us or not? And we didn't know the answer. There is inadequate evidence to support or refute the claims they're effective. I think the jury is still out."
The researchers reviewed dietary studies published between 1966 and February 2003 to evaluate how low-carbohydrate diets affected weight, cholesterol, glucose and insulin levels, and blood pressure. The review covered 107 articles containing data on 3,268 study participants. Of this group, 663 people followed low-carbohydrate diets, meaning they only consumed 60 grams per day or less.
Based on the average 2,000-calorie diet, a person is recommended to consume about 300 grams of carbohydrates daily, according to U.S. Recommended Daily Allowances figures. Only 71 individuals consumed carbohydrates at a rate of about 20 grams per day, the recommended threshold for some of today's most popular diets, such as the Atkins' diet.
As reported in the April 9 issue of the Journal of the American Medical Association -- a special issue on obesity -- the low carbohydrate diet had no adverse effects on cholesterol, glucose, insulin or blood pressure. Among obese patients, weight loss was linked to enduring compliance to the diet -- not the number of carbohydrates that were cut.
Bravata's team pointed out only five of the studies evaluating these diets lasted longer than 90 days, so there is little known about the long-term effects of restricting carbohydrates.
In an accompanying editorial, Dr. George A. Bray of Louisiana State University in Baton Rouge, La., wrote, "Although the truth of 'a calorie is a calorie' has been reaffirmed by the systematic review by Bravata et al., the question of whether patients can adhere more easily to one type of diet or another remains to be answered."
The recent backlash against carbohydrates and growing popularity of low-carb diets is reminiscent of the anti-fat trend from the 1980s, said Dr. Keith Ayoob, a spokesman for the American Dietetic Association and a professor at Albert Einstein College of Medicine in New York.
"Fat had bad PR," Ayoob told UPI, and "carbs have bad PR now. And in both ways it's unfair. People like to wrap it up in a nice, neat package and have absolutes." The tried-and-true proof in dieting is that balanced nutrition, reducing calories to a healthy level, and getting physical exercise all produce weight loss, he said.
"It's a question of how much and how often" you eat, Ayoob explained. This study, "underscores long-term evidence for the value of this kind of a diet that is missing, so therefore, even after all this time, we can't even say it offers any benefits. Losing weight is all about calories and there's a lot of ways of going that, but the more restrictive the calories get, the harder it is to stay on."
According to the U.S. Surgeon General, 61 percent of the U.S. population is either overweight or obese.
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(Reported by Katrina Woznicki, UPI Science News, in Washington)
