Insulin levels are elevated after intense (glycogen-depleting) exercise. This helps replace glycogen stores quickly, but it can result in low blood sugar without dietary carbohydrate, as gluconeogenisis may not be sufficient.
I find that I get pretty darn hungry after HIIT, not only that, but my intervals are quick, I tend to get "delayed onset SWEATHOG MODE ENGAGED. I won't sweat while I workout, I'll walk back up to my hotel room (I only do HIIT when suffering through hotel gyms), and then come the waterworks.
Follow that with an ice cold shower (to try and curb the sweats) and I am even more hungry.
One of the supposed appeals of HIIT is that it increases your metabolic function and keeps your body burning calories throughout the day. I haven't seen any research to back this up, so I'm slightly skeptical still, but it could be part of the reason you're so hungry.
It depends what time of the day I do intervals... If I do them on an empty stomach in the morning or early afternoon, I stuff my face right after or I won't recover at all and I know it. If I do them at night, all I wanna do is drink buckets of water, shower and go to bed.
This used to happen before I started paleo; I would be ravenous for the rest of the day. But after a few weeks of paleo my hunger is much more even. I think this is probably largely due to lowered sugar consumption. I'd just go with it and eat as much as possible, but try not to have too much sugar. I'd stay away from larabars because I've found they tend to make my hunger levels bounce around. I usually have some almonds and some fruit right after my HIIT.
I've experienced this. The first time I did tabata sprints I had this unbelievable craving, I guess I wouldn't even call it hunger, for sugar. Unfortunately I indulged it with probably the worst possible cheat you could ever have - General Tso's chicken. Nasty. Now I make sure I have plenty of sweet potatoes around for afterward.