There's many things at play with caffeine. You have increased heart rate and bp, increased concentration/focus, appetite suppression, etc.. I don't think you

There's many things at play with caffeine. You have increased heart rate and bp, increased concentration/focus, appetite suppression, etc.. I don't think you can point to one effect and say 'this is the one that makes the difference' in a cause and effect kind of way. They are all too related. I personally don't think it matters in this study. You would need another study to pinpoint factors down even more I suppose.