I think that is an issue.
If you have been a yo yo dieter, maybe the mindset is to lose weight, like slimming world for example.
I simply realised I was overeating, so ate less, with a plan not to go back to eating the amount I did.
I also found the Newcastle diet weaned me off food, so apart from the benefit of reversing my diabetes, it gave me a clean slate to plan a new food regime.
As to the "shut down" thing, I had no issue, and many plans like Fung advocate fasting days, and lower calories overall, so it doesn't seem to effect the majority.