andy
how long is your hiit going to last? if what you say is true, that you are new to this type of training, i imagine you wont have much endurance to do a session of hiit for long. so personally, i would do this on an empty stomach.
it all depends on your schedule. if you have all day with nothing to do, then eat well, rest and let the food digest, then do hiit.
if pressed for time, do it on an empty stomach.
i do 1.5 hours interval training on the bike on an empty stomach. anything longer i need a bit of food in me, then it needs to digest before an interval session. everyone is different. again, hiit bike training and hiit lifting training are different.
a friend and training partner who is a national champ in the tri, eats a pbj right before we take off on a hard 4 hour ride.
and another friend who is just as good, eats just a bit before a 4 hour ride.
everyone is different...gotta experiement..
if you are new, be careful jumping right into hiit.