Personal preference. It's thought that cardio on an empty stomach, or fasted cardio will force the body to burn fat for energy, as your stores of glycogen would be depleted due to the fasting. To me that makes some sense.
Some days I do fasted cardio, others I may eat something 2-3 hours prior. I need at least 60-90 minutes pre-cardio to let anything I did eat start to digest, else it comes back up or I get tummy cramps.
Mt Snow, VT - May 5, 2012 - Completed!
...i remain, he who remains to be...