In response to Bloomberg's soda ban, Aaron Carroll calls for "a holistic approach to obesity." He argues that even less draconian policies, such as soda taxes, won't work:
We’d need a pretty high tax [on soda] to make a difference. A recent study showed that it would take a tax on soda of more than 16% to reduce the caloric intake from them by 100 calories per day. But that same study found that almost all of the calories saved from reduced soda intake would likely be replaced by increased calories from other foods and drinks. That’s borne out in research. Partial fixes don’t work. If you ban sugar-sweetened beverages in school, kids will just drink more when they’re not in school.
The Dish 