Diet Coke causes obesity.If Coca-Cola actually told the truth in their TV ads, this is what it might look like.  This faux commercial admits that Coke is partially responsible for America’s obesity epidemic, and exposes the brand’s hundreds of beverages for what they are — empty calories. Even Diet Coke and other “light” or calorie-free options are terrible for you — and people who drink diet soda are even more likely to gain weight! So enjoy this brutally honest Coca-Cola commercial that will never, ever air on television: