I need ideas for a grabber...?

Pretty boring topic, I'm against schools banning junk food. I've been brainstorming for days but I can't think of anything interesting. I want a grabber with a scenario showing that school junk food isn't to blame for kids being obese/unhealthy. They choose to eat unhealthy, it's their lifestyle, it's not the school's problem. And even if the school did serve healthy food, they'd still be unhealthy because they would eat even more junk food at home. How can I incorporate that into something interesting and imaginative?