Losing fat fast.
Personally (although alot of ppl swear by the results)
i wouldnt do a diet which u couldnt maintain all the time.
You pretty much eat maintenance calories and <20g carbs monday to friday then saturday and sunday you "refeed" and eat more carbs to fill up on leptin levels.
prof Greg Ellis, Low Carb Diet Advocate and author of Ultimate Diet Secrets has stated why these diets don't work with pretty good science to back it up saying that re introducing carbs after starvnig your body of carbs at such a rate increases Lipogenesis (Carb to fat conversion) in the liver.