Who says diet drinks aren't harmful?

"A good, in-depth study has found that just one can of diet soda a day can increase your risk of becoming prediabetic. The study suggested that the sweet taste of the artificial sweeteners may actually confuse the brain and cause us to gain weight."

I heard this on Good Morning America this morning. I find it very interesting because I am constantly hearing that diet drinks can't have a bad affect on you. They don't have any calories or any fat so what is the harm? The study includes all artificial sweetners. I don't drink soda but I do drink Crystal Light which I assume has the same affect. Moderation in all things is the way to go!