A good working thesis statement can often be converted into a question, which is typically called your research question. Consider these examples:
Working thesis statement: Younger basketball players "turning pro" continue to ruin the quality of the NBA.
Research question: How have younger professional basketball players ruined the quality of the NBA?
Working thesis statement: The rise in teenage obesity is directly related to the fast food industry.
Research question: What has the fast food industry done to contribute to the rise in teenage obesity?
Notice that neither of these questions can be answered with a simple "Yes" or "No". The "quest" of your research efforts is to find sources that answer your research question.