I won't lie, that first week was a hard slog, I felt horrible to start with mainly due to the sugar dip for the first 5 days. I had been warned about this effect, but I found it really hard to exercise whilst feeling duff. Also had a headache a day for the first 3 days.
Anyway I think I'm over the hump of the sugar dips, 'cause now I'm starting to feel much better, and generally coping with the 1200 cal a day target (thanks to my fitness pal, without which I would be finding this much harder).
The result is that I have lost 2 lb this week, can't ask for more than that I guess.