Guys, I don't know if this helps, but I've just finished reading Johnson's book (well, the science and how-to-do-it bits, anyway), and have learned the following:
1). Once past the initial two weeks, he says you can increase the DD calories if you wish, to a level you find sustainable - and you still get the health benefits. Weight loss may be slower, but fast weight loss that you can't sustain is no good to you - think tortoise and hare. Johnson says some people find it easier to have DD's of between 25-35% of normal calories - but he himself does DD's of 50% much of the time! That would be around 1000 cals for most of us.
2) there're one point where he talks about eating extra calories on a DD if you have exercised. So if you walk briskly for 2 miles, burning 200 cals - your DD level would be around 700 as a minimum
3) A complete fast for 24 hours activates the SiRT gene, the activation is still evident more than 24 hours after the fast has been broken, and then wanes over the next few days. This means that a DD every 3-4 days is sufficient to turn the SiRt gene on and keep it on, which is what gives you all the health benefits, protects lean muscle and inhibits fat storage. Have a look at the picture in chapter 5 of a conveyor belt filling up a vat with DD's/ SIRT activation. Now, the more frequently you do DD's, and the lower your calorie intake on those days, the quicker your vat will fill (full activation). But once it's full - a DD twice a week will keep it topped up, and it takes 21 days without a DD to lose all the benefits. (I'm guessing that this waning over a few days business is the origin of the 5/2 fasting regime described in the Horizon programme - 2 DDs a week would be about the minimum to keep SIRT activated)
If you want to make this weight loss permanent, you need to stick to the programme long-term - and you won't do that if you are so hungry on DD's that you want to chew your own leg off. So, up the calories on your DD's - maybe all of them, maybe just the ones when you feel extra hungry. Be patient, it will work.
PS- I was on a DD yesterday, and although I prefer to eat in the evening, our schedule dictated we eat at lunchtime. I had two wholemeal rolls with low fat egg Mayo, and an apple - that's easily 600 cals. Later on, I was really hungry, and didn't help that DH felt so hungry and shaky he decided to have a bowl of cereal. So, quite late on, I had a cuppa soup - an Ainslie Harriot one, I think it's about 80 cals. I still count it as a successful DD!
Barbara
