FRIDAY, Oct. 5 (HealthDay News) -- Not all diet plans are equally heart-healthy, according to a study ranking eight popular weight-loss programs.

Diets that emphasize a variety of fruits and vegetables scored better than those with a heavy protein focus.

The Ornish diet plan came out on top with the most potential to prevent heart disease risk factors. The Atkins diet came in last, lagging behind the Zone and Weight Watchers.

"It was not surprising to me that the Ornish diet came out on top given that the index used is designed to measure dietary components related to risk of heart disease," said dietician Lona Sandon, a national spokeswoman for the American Dietetic Association.

Sandon said the take-home message for consumers is "if heart disease is your concern, you need to focus more on fruits, vegetables and make all your grains whole grains, as well as limit intake of animal foods and fats."

The findings are published in the October issue of the Journal of the American Dietetic Association.

Researchers at the University of Massachusetts Medical School ranked daily meal plans and food recommendations in the Ornish Plan, the Zone Diet, Atkins, two Weight Watchers plans, the South Beach Diet, the New Glucose Revolution and the 2005 MyPyramid plan.

The rankings were based on the Alternate Healthy Eating Index (AHEI), which uses the daily dietary intake of fruits, vegetables, fats, fiber, nuts, soy and white meats instead of red meat to determine how much benefit a diet has for heart health.

The highest possible score is 70. While none of the diets had a perfect score, they varied across a 20-point spread:

• Ornish, 64.6.
• Weight Watchers high-carbohydrate, 57.4.
• New Glucose Revolution, 57.2.
• South Beach Phase 2, 50.7.
• Zone, 49.8.
• MyPyramid, 48.7.
• Weight Watchers high protein, 47.3.
• Atkins 100-g carbohydrate, 46.
• South Beach Phase 3, 45.6.
• Atkins 45-g carbohydrate, 42.3.

Study author and clinical psychologist Sherry Pagoto said there's no cut-off point in the AHEI scale below which a diet could be definitively considered heart unhealthy. But other studies have ranked low-quality diets in populations at risk for heart disease around the 30-point mark.

"We were most surprised by the fact that the MyPyramid wasn't even in the top three. We figured that this would be a model diet because it is based on the U.S. Department of Agriculture dietary recommendations," Pagoto said.

However, coming in last doesn't mean a diet is of low quality, she said. All of the diets have the potential to be healthy and have been shown in a variety of studies to result in weight loss, which is itself important to improving heart health. Additionally, coming in first does not mean the diet plan is ideal for everyone, she added.

"While the Ornish plan was on top, it's a hard one for most people to follow," Pagoto said. The Ornish plan is a very low-fat, low-calorie, primarily vegetarian diet developed for people who have survived heart attacks, she explained.

In her work counseling clients at the University of Massachusetts Memorial Weight Center, Pagoto said she has learned that it's important for people to be able to stick to the diet plan they choose.

"There is more than one element of a diet to consider," she said.

People with a personal or family history of heart disease should consider the results of this study as a guide when choosing a diet plan, Pagoto said. But they should also think about their food preferences. For example, people who really like carbohydrates would do better with Weight Watchers than with Atkins, regardless of this ranking system, she said.

Pagoto advises patients to keep a food log over several weeks to get a better idea of their food preferences and calorie intake before starting a diet.

Lack of variety courts diet disaster due to boredom, Pagoto said. People will eventually get tired of the limitations of a tightly controlled or hard-to-implement diet, she said.

Despite not making the top three, the USDA's MyPyramid allows for the most variety, she said.

Sandon said: "What I find in working with clients is that most people tend to eat the same foods on a daily or weekly basis and have little variety. They do not want to have to seek out special foods or learn to prepare new foods they are not familiar with. In general, I find that many people in the initial phase of starting a weight-loss plan are more comfortable sticking to a plan of the same foods most of the time but want permission to have something different here and there."

A second study in the same issue of the journal suggests that using canola-based products instead of other oils all the time could meet national standards for healthy fats. Canola oil can help decrease adults' saturated fatty acid intake by up to 9.4 percent and increase their intake of monounsaturated fatty acids by 27.6 percent. Alpha-linolenic acid intake would increase 73 percent. The switch would not affect total calories, fat and cholesterol, according to the researchers, from the University of Illinois and Pennsylvania State University, who studied the diets of more than 9,000 people.

More information

For more about the USDA's dietary guidelines, visit MyPyramid.

SOURCES: Sherry Pagoto, Ph.D., clinical psychologist, assistant professor, University of Massachusetts Medical School, and staff, University of Massachusetts Medical School Weight Center; Lona Sandon, ME.d., R.D., L.D., assistant professor, clinical nutrition, University of Texas Southwestern Dallas; October 2007 Journal of the American Dietetic Association

Copyright © 2007 ScoutNews, LLC. All rights reserved.