I agree with the 100% approach, but in reality it's hard to imagine going for a massive length of time on a bar and two shakes. It's tough. My problem has always been boredom of drinking, and I went throguht Lighter Life for 16 weeks on black coffee, black tea, green tea and water. If I'd known then you could add Coke Zero and Dr Pepper Zero it would really have helped me.
Personally, the total solution is not about not eating anything at all. It's about losing the weight as quickly as I can whilst prepareing my plan for life after VLCD. I understand my mistakes of the past, and so if I cheat, it's about getting back on the horse - that's what post-VLCD life will be about too - if you have a silly meal, don't follow it with another....
Just thought I'd add this, as I see no problem with adding a small jelly or whatever if you keep losing, keep in ketosis and find it helpful - do what works for you.