General Mills Inc...said it will begin using whole grains in all of its breakfast cereals...becoming the latest foodmaker to promote healthier eating...Some big U.S. foodmakers have changed their offerings recently amid America's growing obesity problem. McDonald's Corp. launched meal-sized salads, Kraft Food Inc. [part of Altria] has been promoting the South Beach Diet and Campbell Soup Co. removed artery-clogging transfatty acids from its Pepperidge Farm Goldfish crackers, among other moves.