Washington ( CNN ) -- Nobody seems to have a positive word for Mayor Michael Bloomberg 's proposal to ban oversized servings of sugary drinks in New York 's food-service establishments . The mayor has been decried as a nanny . He has been accused of selective enforcement . ( A Starbucks 20 ounce drink can have more than 500 calories , but will be exempt from the ban because it contains more than 50 % milk . ) The beverage industry complains that solutions to the obesity problem ought to be more `` comprehensive . '' One important conservative magazine called the mayor 's actions a form of `` fascism . '' So let 's defy the trend here and say : Good for Bloomberg . Obesity is America 's most important public health problem , and the mayor has led the way against it . This latest idea may or may not yield results . But it is already raising awareness . Even if it fails to become law , it ought to prod the beverage industry into acting as more responsible corporate citizens . Sugary drinks now provide 7 % of the calories in the American diet , the largest single national source of calories . Teen boys average more than a quart of sugary soda per day . Even adults who say they are trying to lose weight still drink more two 12-ounces cans per day , on average . There is little doubt about the serious health effects of sugary soda . Just one soda a day doubles a woman 's risk of diabetes , according to the Harvard Journals of Public Health . Two sodas raises her risk of heart disease by 40 % . Americans drink more soda for the very simple reason : it 's getting cheaper . The inflation-adjusted price of soda has declined by an estimated 48 % over the past 20 years . Improvements in packaging account for much of this price decline . It costs barely anything more to manufacture a 64-ounce `` double gulp '' container than to produce the former standard sizes . Opinion : Big Gulp ? Meet Big Brother . Some object that the mayor 's proposal to restrict serving sizes will restrict liberty . But the liberty restricted is not the liberty of the soda-drinker . If they wish , soda drinkers can buy a 2-liter bottle of soda at the grocery for about $ 1.70 and pour as much of it down their throats as they wish . The liberty that is being restricted is the liberty of the soda seller to manipulate known human weaknesses to the seller 's advantage and the buyer 's detriment . Human beings are not reasoning machines . We are animals who have inherited certain propensities not always well-adapted to modern urban life . We evolved in conditions of food scarcity . Our bodies have adapted to store food energy against famine ; our subrational minds crave sweetness . The sugary beverage industry has invested massively to understand better how to use our very human natures against us . The ever-increasing size of the standard soda serving has changed our understanding of what is and what is not an appropriate amount of sugar to consume at a sitting . The beverage industry works on Americans before they have learned to read ; even before they have learned to speak . In 2010 , children and teens were exposed to twice as many full-calorie soda TV ads as they were in 2008 , according to a study by the Yale Rudd Center for Food Policy and Obesity . The beverage industry is correct that a soda crackdown alone will not on its own address the obesity problem . Americans spend twice as much time in cars as in the 1970s and average more than 26 hours per week of sedentary entertainment . Some 80 % of Americans do no physical exercise at all . As I 've written before in this space : . `` The campaign against obesity will have to look a lot less like the campaign against smoking ( which involves just one decision , to smoke or not to smoke ) and much more like the generation-long campaign against highway fatalities , which required the redesign of cars , the redesign of highways , and changes in personal behavior like seat-belt use and drunk driving . '' But if a restraint on soda serving size will not do everything , it may still do something . Or possibly not . The idea may fail . The idea is an experiment , and most experiments fail . We learn from failure how to design a better effort next time . And when we do at least succeed in this difficult struggle for public health , we will all owe New York 's visionary mayor our thanks for leading the way . The opinions expressed in this commentary are solely those of David Frum .
New York Mayor Michael Bloomberg being praised for his stance on diabetes . David Koch says the government should be applauded for trying to tackle obesity issue . He says the proposed ban on supersized soda is aimed at sellers , not at buyers ' liberties . Frum : There is little doubt about the serious health effects of sugary soda .