Diet Coke is one of science’s great miracles. Ordinary Coca-Cola relies on lashings of sugar to achieve its trademark sickly sweetness-15.9 grams per can, or about a third of the total daily intake recommended for women by Britain’s National Health Service. A can of Diet Coke, by contrast, contains no sugar at all. It owes its sweetness to aspartame and acesulfame-K, a pair of chemicals that are far sweeter than ordinary sugar, but which provide the body with no energy at all.

That magic combination of sweetness without calories has made artificial sweeteners among the most widely used food additives in a world that is struggling to keep its waistline in check. But people generally dislike the idea of ‘chemicals” in their food, and sweeteners have attracted their share of scare stories. The idea that they cause cancer has proved especially hard to shift, despite no evidence to suggest it is true. A lesser-known (though more respectable) worry is that consuming them might-ironically, and in defiance of common sense-be associated with obesity.

A paper just published in Nature bolsters that view. It provides a […]