I'm just finishing Day Eight which is the Shake Day. The Fast Days are tough, especially when you're doing the workouts, but I'm absolutely wiped out by the Shake Day. Totally depleted and like a limp rag after my intervals. Don't like that at all.
Enjoying the workouts, they slot in pretty well with my current fitness commitments.
Agree with one of the other comments about constipation - got to be really mindful of keeping up the veggies and salads. Otherwise, yep, its only 25 days!
I lost 1.5kg in my first five day cycle - my 18 year old son lost 2.5kg. Let's see where it ends up.