Expect alot of boredom!
And maybe a sore back!
Some eating experiences are different, but it seems most are egg-based.
I had a hard-boiled egg, which I love!
Then all I did was lie down on the hard and narrow scanner table with the scanner over my belly for a long time.
You have to lie down and not move for a LONG time. That is the most difficult part about it. Actually, you can move somewhat, but prefer you keep your torso as still and flat as possible. The tech will tell you and if you are doing too much, he'll tell you to stop what you're doing. I think I could move my arms up and down as long as I was careful to not move my torso during such.
My test was the 1.5 hr version - the minimum it seems. Some make you go longer (2 hrs, etc); others want you to go until it's all gone or half, or whatever. But it does seem they don't want you there longer than 4 hrs.
Imagine lying still on an uncomfortable thing for 4 hrs!
Really, it's a nothing test. Boring at worst and "nice" at best! Try to sleep while on your back; probably the best way to pass time and not move!