WASHINGTON -- Michelle Obama is urging the nation's largest food companies to speed up efforts to make healthier foods and reduce marketing of unhealthy foods to children. Obama asked the companies, gathered at a meeting of the Grocery Manufacturers Association on Tuesday, to "step it up" and put less fat, salt and sugar in foods. "We need you not to just tweak around the edges but entirely rethink the products you are offering, the information that you provide about these products, and how you market those products to our children," she said.