Exercising more cannot replace reducing your calorie intake according to this article in the NYT. That's nothing new but it's so much easier to invite people to move more rather than change their diet, especially if it means antagonizing the very powerful lobbies that benefit from the toxic food and drinks that are the real culprits. Rereading the classic book Prevent and Reverse Heart Disease by Caldwell Esselstyn, it is worth remembering the definite advantage of an all plant diet has been know for at least 20 years: the "First National Conference on the Elimination of Coronary Artery Disease" took place in the summer of 1991. Also recommended is the excellent documentary Forksoverknives.
Of course that's not to say we should not exercise... only that this is NOT the solution to the obesity epidemic, despite what Olympic sponsors Coke and McDo would like you to believe.