“Sugar, alcohol and tobacco,” economist Adam Smith once wrote, “are commodities which are nowhere necessaries of life, which have become objects of almost universal consumption, and which are, therefore, extremely popular subjects of taxation.”

    Two and a half centuries on, most countries impose (征税) sort of tax on alcohol and tobacco. With obesity levels putting increasing pressure on public health systems, governments around the world have begun to toy with the idea of taxing sugar as well.

    Whether such taxes work is a matter of debate. A preliminary review of Mexico's taxation found a fall in purchases of taxed drinks as well as a rise in sales of untaxed and healthier drinks. By contrast, a Danish tax on foods high in fats was abandoned a year after its introduction, during claims that consumers were avoiding it by crossing the border to Germany to satisfy their desire for cheaper, fattier foods.

    The food industry has, in general, been firmly opposed to such direct government action. Nonetheless, the renewed focus on waistlines means that industry groups are under pressure to demonstrate their products are healthy as well as tasty.

    Over the past three decades, the industry has made some efforts to improve the quality of its offerings. For example, some drink manufactures have cut the amount of sugar in their beverages (饮料).

    Many of the reductions over the past 30 years have been achieved either by reducing the amount of sugar, salt or fat in a product, or by finding an alternative ingredient. More recently, however, some companies have been investing money in a more ambitious undertaking: learning how to adjust the fundamental make-up of the food they sell. For example, having salt on the outside, but none on the inside, reduces the salt content without changing the taste.

    While reformulating (再制定) recipes is one way to improve public health, it should be part of a multisided (多边的) approach. The key is to remember that there is not just one solution. To deal with obesity, a mixture of approaches, which include reformulation, taxation and adjusting portion sizes, will be needed. There is nosilver bullet.