I guess the total cost of meth would be hard to calculate, but I'm totally confident that the health costs tied to obesity are far more damaging than meth. Meth just isn't as common as obesity.
Yes, this is precisely the indirect cost I alluded to in my immediately previous comment. That said, far more (several orders of magnitude more) people die from cheeseburgers than (directly or indirectly) from meth. In human lives, McDonald's is by far the greater risk.