The government on Tuesday discarded its one-size-fits-all food pyramid in favor of 12 different triangle-shaped guides, each geared to people's differing lifestyles and nutritional needs.

Inside the familiar pyramid shape, rainbow-colored bands representing different food groups run vertically from the tip to the base. The old pyramid's sections ran horizontally.

Click here to learn more about the new food pyramid.

Agriculture Secretary Mike Johanns (search) called it "a system of information to help consumers understand how to put nutrition recommendations into action."

Also in store are Internet tools to help follow the new recommendations. Officials hope the new symbols will renew interest in healthy habits but acknowledged that it will take time to make a difference in America's growing girth.

People have steadily grown fatter since the food pyramid debuted in 1992. A report last month in The New England Journal of Medicine contended that obesity (search), particularly in children, was causing a reversal in life expectancy, shaving four to nine months off the average life span.

Johanns said the 1992 pyramid had "become quite familiar, but few Americans follow the recommendations."

He said that knowledge about nutrition and food consumption patterns has grown significantly in the past dozen years and is reflected in the new food guidance symbols.

"If we don't change these trends, our children may be the first generation that cannot look forward to a longer life span than their parents," said Eric Bost, the Agriculture Department's under secretary for food, nutrition and consumer services

The new guide is just one element of a system aimed at making people slimmer and healthier, said Eric Hentges, director of the Center for Nutrition Policy and Promotion (search). Also in store are Internet tools to help follow the new recommendations, as well as tools to help educators and nutritionists spread the word.

"Part of the problem previously was that we had this one symbol, this one pyramid, and it was one size fits all," Hentges told agriculture reporters last week. "Or it was a misinterpretation. In the case of grain servings, it said six to 11 servings. Well, if you're supposed to be eating 1,600 calories, you never did get to choose these 11 servings of grain.

"Who knows what a serving is?" Hentges added. "It's whatever I put on my plate. The servings differ for you than for your spouse, maybe."

This time, to make its advice more understandable, the government will switch to cups, ounces and other household measures. The switch was recommended in a 70-page booklet, "Dietary Guidelines for Americans 2005," that was developed by a panel of scientists and doctors and released in January.

The guidelines, which were the basis for revising the pyramid, include eating 2 cups of fruit and 2½ cups of vegetables a day; eating 3 ounces of whole-grain foods a day and drinking 3 cups of fat-free or lowfat milk a day. The government also advises exercising at least 30 minutes a day to reduce the risk of chronic disease, even more to prevent weight gain or maintain weight loss.

In all, there were 23 general recommendations and 18 suggestions for older people, children and other special populations.

That's too much to cram into a symbol that is supposed to be clipped out and stuck to the refrigerator, Hentges said.

The Agriculture Department (search) will offer Web pages that let people appraise their diet and exercise habits. Such a tool has already been available through the agency's Web site; the Interactive Healthy Eating Index (search) has a notice on its home page that it will soon be updated.

Even if the symbol and online tools don't motivate people to change their habits, they'll still have some healthier choices. Food companies have been removing trans fats from their products and adding whole grains because of the government guidance.

"If you get the industry involved and make them feel that they're doing a good thing and that they're getting credit for doing a good thing, they'll do it. They'll change their product," said K. Dun Gifford, president of Oldways Preservation Trust (search), a Boston-based think tank that specializes in food issues.

Critics have raised questions about the public relations agency hired to help create the new version of the pyramid. The firm, Porter Novelli (search), has food companies as clients, but both Agriculture Department and Porter Novelli officials have said the firm's industry work is handled separately and there would be no conflict of interest.

Hentges said his staff of scientists, economists and nutritionists isn't equipped to promote its new approach. If it's not marketed effectively, he said, "then we're not going to be able to get this behavior change or improve anything for Americans."