Ketosis kicks in after 2/3 days as Gems said. Note: After Ketosis before, I flew through week one and two, it was on week 3 I got fed up so its after week 3 (if I get there) that Ill feel more confident on this. I dont want to be negative but I know from past experience that you really have to be vigilant at all times and be careful of the lil voice in your head. So, this time Im trying to be more prepared coz I thought after ketosis Id have no problems with serious hunger, not so for me. But I think it was more mental hunger, old habits resurfacing so not being downbeat, I want to warn people of this. That said, I know this is the only thing that will work for me so Im more prepared this time to get through the hard bits (caused by me, not the diet). All the best to everyone, hope I didnt come across as too negative. At end of day we can all do anything we set our mind too xxx