WASHINGTON - Several of the nation's largest food companies say they are going on a diet. A coalition of retailers, food and beverage manufacturers and industry trade associations said Monday that they will take 1.5 trillion calories out of their products by 2015 in an effort to reduce childhood obesity. That equals about 12.5 calories per person per day.

WASHINGTON - Several of the nation's largest food companies say they are going on a diet.

A coalition of retailers, food and beverage manufacturers and industry trade associations said Monday that they will take 1.5 trillion calories out of their products by 2015 in an effort to reduce childhood obesity. That equals about 12.5 calories per person per day.

The coalition, called the Healthy Weight Commitment Foundation, pledged to reduce the calories as part of an agreement with a group of nonprofit organizations concerned with childhood obesity, first lady Michelle Obama said Monday.

"This is precisely the kind of private sector commitment we need," said Mrs. Obama, who earlier this year launched her own "Let's Move" anti-obesity campaign.

Food companies concerned about national and local efforts to raise food taxes and a rising tide of lawmakers preparing to write anti-obesity measures have publicly endorsed the first lady's message and pledged to make their foods healthier.

The industry foundation said the companies will introduce lower calorie foods, change product recipes and reduce portion sizes to achieve the goal, seeking to reduce 1 trillion of the 1.5 trillion by 2012.

Mrs. Obama has urged the food industry to speed up efforts to produce healthier foods and reduce marketing of unhealthy foods to children. In a speech to an industry association in March, she urged companies not to find creative ways to market products as healthy - including reducing fat and replacing it with sugar, or vice versa - but to increase nutrients as well.

To keep the companies accountable, the Robert Wood Johnson Foundation, a nonpartisan philanthropic and research organization that works to improve the nation's health, will evaluate how the groups' efforts affect the number of calories consumed by children and adolescents.

"We're confident their commitment to this cause is sincere and measurable - and thus has real potential for impact," said Risa Lavizzo-Mourey, president and CEO of the Robert Wood Johnson Foundation. "What remains unknown is what effect it will have on efforts to prevent childhood obesity."

The Healthy Weight Commitment Foundation has more than 80 members, including General Mills Inc., ConAgra Foods Inc., Kraft Foods Inc., Kellogg Co., Coca-Cola Co., PepsiCo Inc. and Hershey Co.