Autistic child with food obsession??!

I know autism is usually associated with food avoidance, but has anyone had experience with the opposite?? I'm talking stealing food, hoarding food, constantly talking about food, hovering in the kitchen etc etc. It has gotten so bad, I've had to lock up my fridge and cupboards because he was sneaking food and flushing the wrappers in the night. He is ten, so definitely old enough to know better. He is very high functioning it is just this one issue really.