(CBS News) New York City Mayor Michael Bloomberg shrugged off criticism of his controversial public health initiatives, saying that "if government's purpose isn't to improve the health and longevity of its citizens, I don't know what its purpose is." Bloomberg most recently put forth a plan to ban the sale of sugary drinks larger than 16 ounces from the city's eateries, street carts and stadiums. The proposal has been sharply criticized, in some cases by beverage and fast food companies as a case of government overreach. He's also been criticized for previous efforts to, among other things, ban smoking in public places and the use of trans-fats in restaurant foods. Some have gone so far as to mock has as being like a "nanny." But on "CBS This Morning," Bloomberg fired back, saying, "We're not here to tell anybody what to do. But we certainly have an obligation to tell them what's the best science and best medicine says is in their interest. If you want to smoke, I think it's pretty ridiculous, you shouldn't. But I don't think we should take away your right to smoke. Bloomberg pointed out that life expectancy iin New York City exceeds the national average by three years, noting that all the progress has come since he took office a decade ago. He brushed aside all the attention the proposed ban has gotten, saying, "That's just because it's the story of the week. That'll get blended into lots of other things. Bloomberg applauded the efforts of some companies that "really understand," such as Coca-Cola, Pepsi and Disney. Coke and Pepsi sell a lot of full sugar drinks, but they're also focusing on smaller cans, Coke in particular. They've put calories on the front to try to tell you. Coca-Cola happens to be one of the companies blasting his proposal. "Anything is OK in moderation," Bloomberg said. Maybe not smoking. But, a full-sugar drink, nothing wrong with it. It's when you drink so much. And it's not the only thing. We have gone to a society where everything is fast food, everything is high calories. The average person today is much heavier than they were. Airlines have a problem: Their customers can't fit in the seats anymore. Bloomberg stressed that, "Obesity is becoming the single biggest health problem in America and will kill more people than smoking in a few years."