@enolf:
It's very much sustainable. It seems (and is) difficult at first. Eventually you get so used to it that it becomes a second nature. Again, it does seem odd, weird, strange, difficult, out of the ordinary, counter-intuitive and all the other adjectives you can come up with. But just trust me, once you get used to it, it will be no problem at all. I think it took me about 3 month to fully adopt and sink in as a part of my life. Now I just do it so naturaly, that any other way seems weird and unnatural.
As for clarity, I agree with you on that one. I wish they had more examples of what to eat. I actually wrote them an email suggesting they should release a complimentary cookbook to go with this book. And they replied saying that they are already working on something like this. I am fine now with the food selection, but it's definetely great for when you are just starting as it seems that you can't eat anything anymore
.
But again, when you learn what's what, then it becomes a second nature. If you were already eating clean, then it should be easier. I had to learn to eat the right way. I used to eat fast food and such. I wasn't an abuser of fast foods, but I did eat there occasionaly. I'd say my diet was an average at best.
I don't think you can count fruits as "free foods". Fruits have tons of calories. You count free foods the foods that have very little or no calories. Like lettuce and cabage and some other ones, I don't remember.
And remember, you don't have to eat every 30 minutes if it's difficult for you. It was a bit of a burden for me (due to the nature of my work and school), so I switched to every hour. Every hour seems perfect for me. Don't make this a hassle for yourself. Enjoy the experience.
The huge benefit I see from this is that I am never hungry. Before I used to be hungry on average of 3-4 hours a day. When I am hungry, I am angry. When I am angry, productivity/creativity decreases. And it just feels good to be always fed!
Good luck. And ask any questions you have, I'll answer anything.