Kyle Gass and Jack Black in 'Tenacious D: the Pick of Destiny'.

Gass and his bandmate JACK BLACK were amazed by the plentiful selection of fattening food available on set.

Gass says, "I got the trainer, I exercised every day, and I got the special diet food delivered to me. I was working as hard as I could. I probably dropped 20 pounds.

"Then we started the movie and there was a full buffet on the set. Somebody must have said, 'Jack and Kyle love to eat. Let's not spare any expense.' We'd have a full breakfast, then craft service would show up with doughnuts and nachos and any snack you can think of.

"When I'm working and there's any sort of pressure at all, I find solace in food. I literally gained it all back.

"We shot the last scene on the first day, when I was still looking crisp and good. But when we finally got around to shooting the earlier scenes, I looked like JABBA THE HUT. I created my own continuity problem."

Source: WENN