I did my first Fast yesterday, having got the book on Thursday and watched "Eat, Fast, Live" on Friday.
I was 96kg a year ago, and got quite ill, my throat so sore I could not eat. I was in effect put on an involuntary fast for a few weeks, and I lost 10kg. Pleased with the result, I continued to eat much less, and by mid-summer was down to 78kg. Since then, my weight steadily crept up to 80kg.
It was such a revelation to see the program and realise the fasting the illness pulled me into was in fact a good thing. I will now take up the 5:2 diet with enthusiasm. My target is to get to about 72kg.
I found yesterday quite easy (2 boiled eggs and a plum for breakfast, Salmon fillet and cherry tomatoes for tea), I think my experience over the last year helped.