In the video, YouTuber Alex Nickel walks through a series of fairly basic experiments to figure out whether Splenda has any "usable calories." To do this he compares the levels of glucose in both sugar and Splenda, since that's the chemical our bodies turn into energy when we digest sugar. The results showed that Splenda actually has more glucose in it than sugar (which Alex points out isn't all that surprising considering Splenda's main ingredient is dextrose, which is a form a glucose). After Alex reached out to Splenda to explain how a packet could contain so much glucose and still claim it's free of calories, a representative got back to him to say that each packet -- roughly a gram's worth of Splenda -- actually contains four calories. Interestingly, that's as many calories that a gram of sugar contains.