clients that when they were on the such and such diet, they lost weight. Now it's all come back plus some and they view that diet as a success. I would say, it wasn't and here's why.
It was one not sustainable for that person. If the process and results were good
A fad diet is still a fad diet. It might have a different name, take less time or whatever, but at the end of the month you're still in the same place you were when you quit the last one. You feel like a big fat failure.
What I discovered was that even though I was doing what I thought I was supposed to do, I wasn't doing what I was meant to do.