WASHINGTON -- The government's plan for a new food pyramid to help fat people lose weight is running into opposition from experts on the panel writing the guidelines for it.

Obesity, the panel members acknowledge, is a problem -- 64 percent of adults and 13 percent of the nation's children are defined as being overweight, according to the government's latest survey in 2001. But some are questioning whether the guidelines are the place for tackling that problem.

At the committee's first meeting this week, some members also said a stronger "eat less, exercise more" message aimed at fat consumers will not reduce obesity. They said the guidelines should continue to focus on helping Americans maintain their present weight.

"It's not that I'm opposed to weight loss," said Russell R. Pate, a fitness expert from the University of South Carolina and an adviser for a food industry research group, the International Food Information Council. "But by focusing on weight maintenance, you're encouraging calorie balance."

The government's current dietary guidelines and food guide pyramid encourage healthy Americans to maintain their present weight by limiting intake of saturated fats, salt and sugar. A revision is due out in 2005.

Two weeks ago, the Agriculture Department said it wanted a new food pyramid accompanying the revised guidelines to focus on inactive, overweight consumers rather than healthy Americans, encouraging moderate eating and exercise to reduce weight.

Gearing the pyramid to healthy people, the department said in a Federal Register notice, "could promote consumption at a level that would increase weight or maintain weight above what is healthy."

At the guideline committee's meeting this week, several members indicated a preference for continuing to target the government's advice to healthy consumers. Critics say that would avoid sending an "eat less" message vehemently opposed by the food industry.

Promoting exercise has been one of the food industry's main responses to accusations that its products, portion sizes and advertising encourage people to overeat.

Michael Jacobson, executive director of the Center for Science in the Public Interest -- which has complained that the panel is dominated by members with ties to the food and pharmaceutical industries -- agreed that encouraging all people to maintain a healthy weight would curb some obesity. But he said both his group and the government want a "clearer and a little stronger" message for those who are overweight.

"Simply telling people to eat less and exercise more is not going to do a darn thing," said Dr. Carlos Arturo Carmargo, who is on the guidelines panel.