Has to be attempted with caution
I bought the Beverly Hills Diet book astounded by the fact that a person may be able to lose weight so quickly.
When I received it I went through the diet list for every single day. I found the fact that she says you can eat anything, but at the same time tells you to eat so little (Nutritionally) on certain days (basing this on the fact that nutritional requirements are based weekly rather than daily) and then eat whatever you please on another day led me to believe that this fad diet helped a person lose a ton of water weight and stay away from processed, toxic foods.
I've tried the diet with my own little twist, (a bit of protein every day, so I don't lose muscle mass, and I exercised too) and lost a hell of a lot of fat weight rather than just water and muscle and everything that's lean tissue.
The author recommends tons of fruit and good foods but in a rather low calorie count and spreads out the nutrition on a weekly basis.
If you use a bit of common sense and stick to some basic nutritional guidelines (never skip out on any food group especially proteins) and you workout for all those 35 days, it's a pretty healthy diet.
* Exercise is a CRUCIAL part of any diet if you want to maintain the healthy parts of your body (Lean tissue: muscle etc.) and reduce fatty deposits