She (or Si, can't remember) did say you need water to digest the food and hence need to stay hydrated.I think the coffee star jump thing is dangerous. I disagree with a few things she says about weight, you need to be hydrated. You’ll lose weight naturally as you go around anyway.
My tip is lay off stims a week before then when you hit the caffeine gels you’ll really feel them.
TBH, never even thought of coffee and star jumps ... just sounds 'wrong' in so many ways
The fibrous food though does sound logical to me, if the body is slow to 'move' food through the gut. Gives me an excuse before ToC to eat bread and cakes the day before rather than fruit 
But then she didn't say not to drink it, so it might be OK 

Just make sure you're near a loo

life is too short for keep coming in last 

. Having a turbo the last couple of months has definitly helped me up the power a bit. But I have a nagging feeling that not getting out on the bike much hasn’t done my endurance many favours. From what you’ve said recently and seeing your progress on swift I think you’ve managed to get a good balance between the two.