@Skylarking953 you have some great questions and we're all asking similar things. I still feel like we're in the very early stages of this, so the proof of the pudding is yet to be realised as we've not been following this WoE long enough to show true and lasting evidence of its efficacy.
I can only offer my own opinion and experience from the last few months, hopefully it will be of some benefit and perhaps answer some questions you have.
Firstly, I do get why he doesn't call it a diet. It's not something we can do over a few weeks and see a result from, but it's a new long-term way of eating to (hopefully!) result in long-term benefits.
However there are similarities to other diets in that certain foods are to be reduced or cut out of regular eating, so in that sense it is a diet of sorts.
What I will say is that it feels VERY different to diets I've done in the past. No counting calories or points or syns, no weighing portions, no absolutely rigid 'rules' that will see us fail and give up if we eat something off-plan.
For me this means it is a much more sustainable way of eating that I know I can maintain long-term.
I have lost over 2 stones in 4 months and in that time I have continued to have occasional takeaways, birthday cake, occasional desserts and meals out. I have not felt deprived or hungry and I have not resented following the plan.
Previously on diets I have been so hungry and have thought constantly about food, I've resented counting points and weighing portions, I've hated waking up and realising it was a fast day so I couldn't have breakfast and I've always given up and packed it in after a few months because it was unsustainable for me to maintain the restrictions and discipline the diet demanded.
I genuinely believe I can eat this way for the rest of my life. I also know that I can have days when I'm not following the plan (as when I was on holiday, or joining in with birthday celebratory cake) and it will not have too much effect.
I realise it's still early days, but so far this feels like it could make the difference for me regarding my long-term weight and health prospects.