WASHINGTON >> Commercials promoting sugary breakfast cereals could be put on a strict diet under government guidelines urging food companies to limit marketing of unhealthy products to children.

Under a proposal announced Thursday by several government agencies, companies would be urged to only market foods to children ages 2 through 17 if they are low in fats, sugars and sodium and contain specified healthy ingredients.

The guidelines set parameters that are stricter than many companies have set for themselves and, if the companies agree, would eliminate much of the advertising consumers see now — on television, in magazines, in stores and on the Internet — for foods that appeal to children.

If many companies sign on to the guidelines, children could see much less of the colorful cartoon characters used to advertise cereals or other gimmicks designed to draw their attention. If the companies wanted to continue that advertising, they would have to reduce unhealthy ingredients in their products.

The food industry has been successful in reducing the number of television ads aimed at children in recent years and much of that advertising has moved to the Internet, social media and other digital platforms such as smart phones. Public health advocates have argued that the industry’s self-regulation is not enough and has pushed the government to set guidelines.

In 2009, Congress directed the Federal Trade Commission, Agriculture Department, Food and Drug Administration and the federal Centers for Disease Control and Prevention to form a working group and develop the recommendations. The guidelines they wrote are broad, applying to almost any promotion a child might see for a food — including text messages, product placement in video games and celebrity endorsements.

The agencies said the proposal, which would be phased in over five years and is up for public comment until the summer, is "to encourage a marketing environment that supports, rather than undermines," parents’ efforts to get children to eat healthy food.

"While the goals (the guidelines) would set for food marketers are ambitious and would take time to put into place, the public health stakes could not be higher," the working group said in a statement. "One in three children is overweight or obese, and the rates are even higher among some racial and ethnic groups."

Specifically, the agencies recommend that companies only market foods that have a significant amount of fruits, vegetables, whole grains, low-fat milk products, fish, extra lean meat, eggs, nuts, seeds or beans. Foods that have any trans-fat, more than 1 gram of saturated fat, more than 13 grams of added sugars or more than 210 milligrams of sodium in a serving would not be eligible for marketing to children.

The agencies suggest the industry focus its efforts on foods that are most heavily marketed to children, including breakfast cereals, carbonated beverages, restaurant foods and snack foods.

Sen. Tom Harkin, D-Iowa, who authored the original bill asking for the guidelines, said Wednesday he is pleased with the agencies’ recommendations.

"Kids are being bombarded daily with ads for unhealthy foods and it is long past time that we limit the amount of junk food advertising," he said.

It is unclear whether government pressure will be effective enough to get many companies to sign on. Some of the country’s largest food companies, including McDonalds, General Mills Inc., Kellogg Co., Kraft Foods Global and PepsiCo Inc., already have joined an initiative sponsored by the Better Business Bureau to limit their marketing to children. The standards are similar but not as strict.

Scott Faber, lobbyist for the Grocery Manufacturers Association, says the industry has reformulated recipes to adhere to those standards as it has also limited marketing of the unhealthiest foods. He says the number of food ads on children’s shows has fallen by half since 2004.

"The number of ads for cookies, candy, soda and snacks has dropped even more dramatically," he said.

As they have had to move away from marketing to kids, many food companies are stepping up efforts to reach the primary shoppers in family households, which are often moms. More ads are popping up on blogs directed at mothers and recipe sites.

The food industry’s efforts to change recipes and limit advertising have come as consumers are increasingly educated and aware of what they are eating. The president’s wife, Michelle Obama, also has been leading a campaign to fight childhood obesity.

Still, public health advocates say they believe a lot of work remains. Margo Wootan, director of nutrition policy at the advocacy group Center for Science in the Public Interest, says advocates hope the guidelines will make a greater impact.

"As a mom watching television with my daughter or walking through the aisles of the supermarket, it seems like nothing has changed," she says. "If companies applied these standards it would get rid of almost all junk food marketing to kids."