How can sweeteners contain no calories, and how do metal detectors work?

We explore the curious questions that science can answer

Sugarcoated science: sweetness and calories are not measured in the same way (Getty/iStock)

How can artificial sweeteners taste like sugar yet contain no calories?

Sugar is very sweet and has a high energy content, or calorific value. But sweetness and calorie content aren’t necessarily linked.

Sweetness – which is a difficult property to measure, unlike calories – appears to be caused by a different chemistry to calorie content. In fact, we can record sweetness only through taste tests.