I should start by saying that this is in no way meant to be judgemental. I have noticed that there seem to be three main types of diets out there:
1) Crash diets - short-term, more extreme, sometimes meant to be used for minor weight loss or detox. I'd guess that many if not most forum members here have tried these, but most are on one of the other two options.
2) Phased diets - Atkins, 17 Day Diet, anything which involves different stages.
3) Long-term steady diets - anything where you keep on doing roughly the same thing long-term.
I'm talking about weight loss here, not maintenance, which obviously is a different matter. If the diet involves a major change apart from mere quantity in the maintenance phase (e.g. entire food groups being moved on or off the list of allowed foods), then it's probably a phased diet.
Our culture has a very strange attitude towards both weight and weight loss, and as well as promoting unrealistic ideals of beauty, also promotes unrealistic ways of dieting. People are encouraged to think that there is a quick fix, and then if this doesn't work for them - and it rarely works for anyone in the long term - they often end up blaming themselves and may get twisted up into guilt patterns.
I suspect that when one of the first two types of diet don't work, it's because there are no quick fixes, but people hope that there are, and will try to form an uneasy compromise between the quick fix ideal and the realities of long-term weight loss. So they start a crash diet because it promises instant results, and then think why not keep going if it's worked so well so far, and of course it's not sustainable long-term and this is where yo-yo dieting comes from.
With phased diets, I have known countless people prolong one of the earlier phases because that's when the more rapid weight loss occurs. I don't know how far weight loss is more rapid in "induction" phases because it's a more extreme diet at that point, and how far it's because most people lose weight faster to begin with anyway. I do know that it's where a phased diet is vulnerable to going wrong, which can create difficulty with compliance, an unbalanced diet and perhaps health problems. People cutting out carbohydrates long-term on Atkins instead of gradually adding a certain amount back, for instance, and definitely a lack of vegetables! Of course, phased diets work beautifully for many people, and I'm sure there can be advantages to tackling weight loss in stages, but this is a particular problem which they are open to.
As far as I know, the general pattern with phased diets is that they are more restrictive to begin with, sometimes to crash/detox diet levels, and then gradually become less restrictive. There is also the approach to dieting where the diet starts off gently and becomes gradually less restrictive, and I think this is more commonly an informal approach, where someone makes it up as they go along. For example, starting off by switching soft drinks to diet versions, then eliminating those, then stopping certain types of junk foods, then introducing wholegrains, that sort of pattern. I'm not thinking of that as a formal phased diet, it's the externally-imposed structures I'm thinking of here, but if I'm wrong, please let me know.
I've occasionally glanced thoughtfully at detox regimes, but never felt I was strong enough to handle them, and ended up on plain calorie counting, so I don't have personal experience here. I'm very interested to know what other people have found.

I hadn't had my coffee yet. I just don't think I agree entirely with what you're saying.
Some people have huge success on the plans that haven't worked for me. It's all so individual. There is so much variety. I don't place blame ANYWHERE in that equation. We're all just perpetually shoe-shopping.
