Burns more brown fat but doesn't save glycogen. And how often is performance limited by availability of fatty acids?
To be fair, most people feel stronger or more focused when they take it, so it must stave off some people's premature decisions to slow down or quit.
Just doesn't compute when people use it before a normal workout or pretend it's physiology science gains rather than a willpower crutch.
Tim Noakes fanboy if you can't tell already..