Hostess Brands Inc. filed for Chapter 11 bankruptcy protection Wednesday to confront burdensome debt and labor costs that the Twinkies and Wonder Bread baker says have left it fighting to compete.

The privately held Irving, Texas, company's move marks the second significant court restructuring in the past several years. In a statement, Hostess said the current cost structure "is not competitive, primarily due to legacy pension and medical benefit obligations and restrictive work rules." It said it would be able to maintain...