Calorie Accounting

NPR reported this morning on the state of obesity in Mexico (It's actually worse than in the U.S., which makes you wonder what's up with North America.) and what policymakers are doing to address this public health issue. Could a tax on high-calorie foods and sodas really induce the public to drink more water, as one interviewee suggests? What are the potential economic effects of a high-calorie food and soda tax or other economic incentive/disincentive programs to prevent public health issues?

http://www.chicagomag.com/Chicago-Magazine/January-2009/Junk-Food/