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4 Popular Diets Heart Healthy

Whether it's Atkins, Ornish, Weight Watchers or Zone, it's the pounds that matter

Low-Carb vs. Low-Fat

Dansinger studied 160 overweight men and women who volunteered to participate in a yearlong diet study. Forty volunteers were assigned to each diet, he says. Dansinger says he was "just testing the diets, not any exercise or other lifestyle modifications that are part of the entire diet program." The researchers also calculated a score to estimate a person's heart disease risk -- based on common heart disease risk factors, such as cholesterol and blood pressure.

The benefits from the diets were limited to those who carefully followed them -- and following the diets was no easy task since the drop out rate for each diet was 22% at two months. By one year half of the volunteers assigned to Atkins or Ornish had dropped out as had 35% of those assigned to Weight Watchers or Zone diets.

Participants following the Atkins, Weight Watchers, and Zone diets achieved significant reductions in the heart risk score. Those following the Ornish diet did not show any significant improvement in the heart disease risk score.

Dansinger tells WebMD that this does not mean that the "Ornish diet doesn't reduce heart disease risk. I have great faith in the Ornish diet, but it did not meet the statistical test in this study."

Ornish Responds

Dean Ornish, MD, founder and president of the Preventive Medicine Research Institute in Sausalito, Calif., was immediately critical of the results.

Ornish tells WebMD that the people assigned to his diet "lost more weight, had greater reductions in LDL (the 'bad' cholesterol), and were the only dieters to significantly lower insulin -- even though the Atkins and Zone diets claim to be specifically designed to lower insulin." Lower insulin levels indicate a lower risk of developing diabetes, another powerful heart disease risk factor.

Dansinger, who joined Ornish in fielding questions from reporters, agrees that the Ornish diet posted impressive results for those who stayed the course for a year: a nearly 20% reduction in insulin levels while the Atkins diet dropped insulin by about 8% and the Zone was associated with a 17% drop in insulin.

Likewise, the Ornish diet reduced LDL cholesterol by 17%, while the Atkins dieters reduced LDL by 9%, followed by Weight Watchers dieters at 8% and Zone dieters at 7%.

Good Cholesterol: How Important Is It?

But the heart disease risk score is based on the ratio between LDL cholesterol and HDL "good" cholesterol.

"The Ornish diet does not increase HDL, while the other diets do achieve significant increases in HDL," says Dansinger. The Atkins and Zone diets increased HDL by 15%, while Weight Watchers posted an 18.5% gain. But the Ornish diet increased HDL by just 2.2%.

Ornish says HDL is not really a factor because "HDL is really like a garbage truck that goes around picking up the garbage, which is bad cholesterol. When you don't have as much bad cholesterol -- garbage -- you don't need as many garbage trucks." He adds, "raising HDL is easy: eat a stick of butter. That will drive up your HDL, but it's not good for you."

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