Having done it I would say its not much of a challenge if you are moderately fit. But if you don’t act like a dick, donate to mountain rescue and know what you are doing the it’s not too bad.
As for 8000 calories I think that is a bit OTT. Basically if you want to do it in 24 hrs you need something you can eat in the back of a car.
I had a few caffeine gell things, 2 pot noodles and some instant porridge. The drivers put hot water in flasks while we walked which was very useful.
We also did it in the pissing rain so I was glad of 3 sets of clothes and lots of space in the minibus to dry things. 16 people in an 16 sweater would not be much fun.