As someone guilty of the occasional "zero calorie" drink, I've often been super confused by this. How can drinks be sweetened without adding calories? This video breaks down the science.
The video above - created by a terrifyingly precocious kid of all people - does a really good job of explaining some of the bullshit surrounding zero calorie sweeteners. It's scary stuff.
Turns out most sweeteners actually do contain calories. A fair amount of them actually, but a loophole allows them to present as zero calorie. Utterly bizarre.
Well worth watching.