Usually it will be either tied to spam for a water machine or a testimonial of someone who says it cured them, but they don't stay long. There is not any compelling study evidence of general value that I know of.
We do have one member who went on a diet of the same scheme and reported improvements, but I don't suggest that there is a curative power there.
The placebo effect could easily be at work. If you are motivated, you'll do a lot of things to improve your diet and general health, which as a whole will likely benefit you.