A nutritious diet is one of the key ways to stay physically and mentally fit. Research suggests it may reduce your risk of developing various conditions, including type 2 diabetes , heart disease and certain cancers. Diet may also help protect against depression and other mental health concerns. But for some people, eating so-called "clean" foods can become an obsession. And social media can exacerbate this. So what is "clean eating"? And when could it be harmful? A concerning trend The term "