Interesting. Their two-week adaptation time is consistent with what I noticed in myself. I don't do the diet this strictly. I simply commented to a trainer that I have never been able to successfully work out hard- meaning weight lifting an anaerobic interval training- and lose weight simultaneously.

He suggested I try working out while fasting. Just don't eat 3-4 hours before working out, and have a high quality protein 'meal' (I drink a shake) after the workout.

So far it's been working for me. And I've been working out since I was a young teenager- some three dozen years now.