A long-running comparison of three diet plans found that the low-carbohydrate Atkins regimen and a Mediterranean diet rich in fish and nuts produced slightly greater weight loss than a low-fat program modeled on American Heart Assn. dietary guidelines.
The low-carb dieters, who consumed generous amounts of saturated fat but avoided such staples as bread and pasta, saw steeper increases in HDL, or good, cholesterol than people on either the Mediterranean or low-fat diet, according to a report in today's New England Journal of Medicine.
The study, funded in part by the Dr. Robert C. and Veronica Atkins Foundation, was the latest to demonstrate the benefits of diets high in fat, protein and cholesterol, which had long been considered unhealthful.
"It is time to reconsider the low-fat diet as the first choice for weight loss and for cardiovascular health," said study author Dr. Meir J. Stampfer of the Harvard School of Public Health. "It is not the best."
The average weight loss in all three diet plans was small, and participants regained some of their pounds before the two-year study was over. Atkins dieters lost an average of 12 pounds; those on the Mediterranean regimen -- which included nuts, fish and olive oil -- shed an average of 10 pounds; and people assigned to the low-fat program lost an average of 7.3 pounds.
The study tracked 322 moderately obese people, all employees of a nuclear research facility in Israel, who were randomly assigned to one of the three diets. The average age of participants was 52, and most were men.
The low-fat diet, in which 30% of calories came from fat, and the Mediterranean diet had daily calorie restrictions. Men were limited to 1,800 calories, women to 1,500 calories.
People on the low-carb diet had no calorie limit but were encouraged to choose vegetarian sources of fat, such as beans and nuts, more than commonly associated with the Atkins diet. Their intake of carbohydrates was limited to 120 grams daily, compared with 400 grams in the typical U.S. diet.
To help participants stick to their programs, the workplace cafeteria prepared special meals for them and nutritional counseling was also available at work. Spouses were trained in how to keep participants encouraged, and participants tracked what they ate.
By the end of the study, subjects in all groups were consuming fewer calories and exercising more.
People on low-carb diets saw the greatest improvements in their HDL cholesterol and in a key ratio of total cholesterol to HDL cholesterol that is used to assess cardiac risk. That ratio fell 20% in low-carb dieters, 16% in those on a Mediterranean diet and 11.5% in low-fat dieters.
Every 1% decline in the ratio represents a 2% drop in overall odds of developing cardiovascular disease, said lead author Dr. Iris Shai of Ben-Gurion University of the Negev in Israel, which also funded the study. "It is easy to identify the enemy -- it is bread, potatoes, pasta and rice," she said.
Although the study ended in June 2007, participants are being tracked to see how well they follow their diets without special workplace meals and counseling, Shai said.
Kelly Brownell, director of the Yale Center for Eating and Weight Disorders, who was not involved in the study, said that it should not be taken as a victory for low-carb diets because the people on the Mediterranean diet showed similar benefits. They also had an easier time maintaining their weight loss during the course of the study, he said.
Dr. Robert H. Eckel, a past president of the American Heart Assn. and a professor of medicine at the University of Colorado Health Sciences Center, said he was not ready to recommend an Atkins-type diet based on the study results.
People on low-carb diets increase consumption of saturated fat, which cannot be good for them in the long run, he said. LDL, or bad, cholesterol did not improve in any of the diet groups, said Eckel, who was not involved in the study.
Marion Nestle, a professor of nutrition, food studies and public health at New York University, who also was not involved in the study, said she wasn't that impressed with the benefits of any of the diets. The gains were meager, she said, and the effort to achieve them great. The study did not change her basic approach to weight loss: "Eat less, move more," she said.
The co-sponsor Atkins Foundation was founded by the widow of Dr. Robert Atkins, who developed the diet that carries his name, but it is not affiliated with and operates independently of Atkins Nutritionals Inc.