For years, the Atkins formula of sparing carbohydrates and loading up on taboo fatty foods has been blasphemy to many in the health establishment, who view it as a formula for cardiovascular ruin.
But now, some of the same researchers who long scoffed at the diet are putting it to the test, and they say the results astonish them. Rather than making cholesterol soar, as they feared, the diet actually appears to improve it, and volunteers take off more weight.
However, because the number of patients studied so far is small, experts are not yet recommending a change to orthodox guidelines on heart healthy diets, which tend to recommend the low-fat approach.
At least three formal studies of the Atkins diet have been presented at medical conferences over the past year, and all have reached similar results.
The latest, conducted by Dr. Eric Westman of Duke University, was presented Monday at the annual scientific meeting of the American Heart Association, long a stronghold of support for the traditional low-fat approach.
In research financed by the Robert C. Atkins foundation in New York City, which promotes the Atkins diet, Westman studied 120 overweight volunteers. They were randomly assigned to the Atkins diet or the heart association's Step 1 diet, a widely used low-fat approach. On the Atkins diet, people limited their carbs to less than 20 grams a day, and 60 percent of their calories came from fat.
After six months, the people on the Atkins diet had lost 31 pounds, compared with 20 pounds on the AHA diet, and more people stuck with the Atkins regimen.
Total cholesterol fell slightly in both groups. However, those on the Atkins diet had an 11 percent increase in HDL, the good cholesterol, and a 49 percent drop in triglycerides. On the AHA diet, HDL was unchanged, and triglycerides dropped 22 percent. High triglycerides may raise the risk of heart disease.
While the volunteers' total amounts of LDL, the bad cholesterol, did not change much on either diet, there was evidence that it had shifted to a form that may be less likely to clog the arteries.
"More study is necessary before such a diet can be recommended," Westman said. "However, a concern about serum lipid (cholesterol) elevations should not impede such research."
No single study is likely to change minds on the issue, especially since initial weight loss is hard to maintain on any diet. Some answers could come from a yearlong study being sponsored by the National Institutes of Health that will test the Atkins diet on 360 patients.
Dr. Alice Lichtenstein, a nutrition expert at Tufts University, said she thinks too much is made of the amounts of carbohydrates and fats in people's diets as they try to shed weight.
"There is no magic combination of fat versus carbs versus protein," she said. "It doesn't matter in the long run. The bottom line is calories, calories, calories."
Other reports at the meeting conformed more to conventional wisdom. The association recommended people with heart disease eat one serving of oily fish a day. Research presented there suggested that fruits and vegetables lowered the risk of obesity, and that obesity or frequent weight swings in old age increased risk of heart attack among women.